Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /usr/bin/ruby1.8 extconf.rb


Gem files will remain installed in /usr/lib/ruby/gems/1.8/gems/capybara-webkit-0.12.1 for inspection.
Results logged to /usr/lib/ruby/gems/1.8/gems/capybara-webkit-0.12.1/./gem_make.out
An error occurred while installing capybara-webkit (0.12.1), and Bundler cannot continue.
Make sure that `gem install capybara-webkit -v '0.12.1'` succeeds before bundling.