rails s
/usr/local/share/gems/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require': cannot load such file -- mysql2/mysql2 (LoadError)
        from /usr/local/share/gems/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `block in require'
        from /usr/local/share/gems/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:236:in `load_dependency'
        from /usr/local/share/gems/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
        from /usr/local/share/gems/gems/mysql2-0.3.15/lib/mysql2.rb:8:in `<top (required)>'
        from /usr/local/share/gems/gems/bundler-1.5.3/lib/bundler/runtime.rb:76:in `require'
        from /usr/local/share/gems/gems/bundler-1.5.3/lib/bundler/runtime.rb:76:in `block (2 levels) in require'
        from /usr/local/share/gems/gems/bundler-1.5.3/lib/bundler/runtime.rb:72:in `each'
        from /usr/local/share/gems/gems/bundler-1.5.3/lib/bundler/runtime.rb:72:in `block in require'
        from /usr/local/share/gems/gems/bundler-1.5.3/lib/bundler/runtime.rb:61:in `each'
        from /usr/local/share/gems/gems/bundler-1.5.3/lib/bundler/runtime.rb:61:in `require'
        from /usr/local/share/gems/gems/bundler-1.5.3/lib/bundler.rb:131:in `require'
        from /var/www/redmine-2.5.0/config/application.rb:7:in `<top (required)>'
        from /usr/local/share/gems/gems/railties-3.2.17/lib/rails/commands.rb:53:in `require'
        from /usr/local/share/gems/gems/railties-3.2.17/lib/rails/commands.rb:53:in `block in <top (required)>'
        from /usr/local/share/gems/gems/railties-3.2.17/lib/rails/commands.rb:50:in `tap'
        from /usr/local/share/gems/gems/railties-3.2.17/lib/rails/commands.rb:50:in `<top (required)>'
        from script/rails:6:in `require'
        from script/rails:6:in `<main>'