[JRO] Upgrade to Rails 4

* Remove unecessary gems
* Update to rails 4 in gemfile
* Remove griddler email processor
* Remove client-side-validations
* remove jquery-rails from gemspec

* Subclass the correct base controller
  It was finding ::ApplicationController and not
  Thredded::ApplicationController so specifying the
  correct base class fixes the issue
[JRO] Upgrade friendly_id