Enable JRuby support for AR

Right now this is just an experiment, I'm enabling JRuby support for
ActiveRecord (with `allow_failures` option on Travis), we'll see how it goes.
Add facebook display setting in the initializer
temporarily set jruby tests only for rails4
Cleaning up
Cleaning up unused integration spec
Add jruby builds for mongoid and mongo_mapper (Rails 4.x)
Merge pull request #590 from NoamB/separated-adapters

Separated adapters from model #581
Merge pull request #588 from arnvald/experimental_jruby_support

Enable JRuby support for AR
Merge pull request #600 from rogercampos/initializer_fb_display_setting

Add facebook display setting in the initializer
Fixed adapter calls in submodules
Global controller specs #586
Cleanup