Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - laravel/laravel v5.2.0 requires laravel/framework 5.2.* -> satisfiable by laravel/framework[v5.2.0, v5.2.1, v5.2.10, v5.2.11, v5.2.12, v5.2.13, v5.2.14, v5.2.15, v5.2.16, v5.2.17, v5.2.18, v5.2.19, v5.2.2, v5.2.20, v5.2.21, v5.2.22, v5.2.23, v5.2.24, v5.2.25, v5.2.26, v5.2.27, v5.2.28, v5.2.29, v5.2.3, v5.2.30, v5.2.31, v5.2.4, v5.2.5, v5.2.6, v5.2.7, v5.2.8, v5.2.9].
    - laravel/laravel v5.2.15 requires laravel/framework 5.2.* -> satisfiable by laravel/framework[v5.2.0, v5.2.1, v5.2.10, v5.2.11, v5.2.12, v5.2.13, v5.2.14, v5.2.15, v5.2.16, v5.2.17, v5.2.18, v5.2.19, v5.2.2, v5.2.20, v5.2.21, v5.2.22, v5.2.23, v5.2.24, v5.2.25, v5.2.26, v5.2.27, v5.2.28, v5.2.29, v5.2.3, v5.2.30, v5.2.31, v5.2.4, v5.2.5, v5.2.6, v5.2.7, v5.2.8, v5.2.9].
    - laravel/laravel v5.2.23 requires laravel/framework 5.2.* -> satisfiable by laravel/framework[v5.2.0, v5.2.1, v5.2.10, v5.2.11, v5.2.12, v5.2.13, v5.2.14, v5.2.15, v5.2.16, v5.2.17, v5.2.18, v5.2.19, v5.2.2, v5.2.20, v5.2.21, v5.2.22, v5.2.23, v5.2.24, v5.2.25, v5.2.26, v5.2.27, v5.2.28, v5.2.29, v5.2.3, v5.2.30, v5.2.31, v5.2.4, v5.2.5, v5.2.6, v5.2.7, v5.2.8, v5.2.9].
    - laravel/laravel v5.2.24 requires laravel/framework 5.2.* -> satisfiable by laravel/framework[v5.2.0, v5.2.1, v5.2.10, v5.2.11, v5.2.12, v5.2.13, v5.2.14, v5.2.15, v5.2.16, v5.2.17, v5.2.18, v5.2.19, v5.2.2, v5.2.20, v5.2.21, v5.2.22, v5.2.23, v5.2.24, v5.2.25, v5.2.26, v5.2.27, v5.2.28, v5.2.29, v5.2.3, v5.2.30, v5.2.31, v5.2.4, v5.2.5, v5.2.6, v5.2.7, v5.2.8, v5.2.9].
    - laravel/laravel v5.2.27 requires laravel/framework 5.2.* -> satisfiable by laravel/framework[v5.2.0, v5.2.1, v5.2.10, v5.2.11, v5.2.12, v5.2.13, v5.2.14, v5.2.15, v5.2.16, v5.2.17, v5.2.18, v5.2.19, v5.2.2, v5.2.20, v5.2.21, v5.2.22, v5.2.23, v5.2.24, v5.2.25, v5.2.26, v5.2.27, v5.2.28, v5.2.29, v5.2.3, v5.2.30, v5.2.31, v5.2.4, v5.2.5, v5.2.6, v5.2.7, v5.2.8, v5.2.9].
    - laravel/laravel v5.2.29 requires laravel/framework 5.2.* -> satisfiable by laravel/framework[v5.2.0, v5.2.1, v5.2.10, v5.2.11, v5.2.12, v5.2.13, v5.2.14, v5.2.15, v5.2.16, v5.2.17, v5.2.18, v5.2.19, v5.2.2, v5.2.20, v5.2.21, v5.2.22, v5.2.23, v5.2.24, v5.2.25, v5.2.26, v5.2.27, v5.2.28, v5.2.29, v5.2.3, v5.2.30, v5.2.31, v5.2.4, v5.2.5, v5.2.6, v5.2.7, v5.2.8, v5.2.9].
    - laravel/laravel v5.2.31 requires laravel/framework 5.2.* -> satisfiable by laravel/framework[v5.2.0, v5.2.1, v5.2.10, v5.2.11, v5.2.12, v5.2.13, v5.2.14, v5.2.15, v5.2.16, v5.2.17, v5.2.18, v5.2.19, v5.2.2, v5.2.20, v5.2.21, v5.2.22, v5.2.23, v5.2.24, v5.2.25, v5.2.26, v5.2.27, v5.2.28, v5.2.29, v5.2.3, v5.2.30, v5.2.31, v5.2.4, v5.2.5, v5.2.6, v5.2.7, v5.2.8, v5.2.9].
    - laravel/framework v5.2.9 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.8 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.7 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.6 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.5 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.4 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.31 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.30 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.3 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.29 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.28 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.27 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.26 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.25 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.24 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.23 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.22 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.21 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.20 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.2 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.19 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.18 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.17 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.16 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.15 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.14 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.13 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.12 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.11 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.10 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.1 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - laravel/framework v5.2.0 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - Installation request for laravel/laravel ^5.2 -> satisfiable by laravel/laravel[v5.2.0, v5.2.15, v5.2.23, v5.2.24, v5.2.27, v5.2.29, v5.2.31].

  To enable extensions, verify that they are enabled in those .ini files:
    - /etc/php/5.6/cli/php.ini
    - /etc/php/5.6/cli/conf.d/10-opcache.ini
    - /etc/php/5.6/cli/conf.d/10-pdo.ini
    - /etc/php/5.6/cli/conf.d/20-calendar.ini
    - /etc/php/5.6/cli/conf.d/20-ctype.ini
    - /etc/php/5.6/cli/conf.d/20-exif.ini
    - /etc/php/5.6/cli/conf.d/20-fileinfo.ini
    - /etc/php/5.6/cli/conf.d/20-ftp.ini
    - /etc/php/5.6/cli/conf.d/20-gettext.ini
    - /etc/php/5.6/cli/conf.d/20-iconv.ini
    - /etc/php/5.6/cli/conf.d/20-json.ini
    - /etc/php/5.6/cli/conf.d/20-phar.ini
    - /etc/php/5.6/cli/conf.d/20-posix.ini
    - /etc/php/5.6/cli/conf.d/20-readline.ini
    - /etc/php/5.6/cli/conf.d/20-shmop.ini
    - /etc/php/5.6/cli/conf.d/20-sockets.ini
    - /etc/php/5.6/cli/conf.d/20-sysvmsg.ini
    - /etc/php/5.6/cli/conf.d/20-sysvsem.ini
    - /etc/php/5.6/cli/conf.d/20-sysvshm.ini
    - /etc/php/5.6/cli/conf.d/20-tokenizer.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

Installation failed, deleting ./composer.json.