Make delete provider work.

* The issue mentioned here was affecting it:
  http://martinciu.com/2011/07/difference-between-class_inheritable_attribute-and-class_attribute.html
Fix 'Card Activity' page.

* Streaming in Rails 4 is no longer done using: render :text => proc {}
  It is done using response_body or using Live streaming (response.stream).

* Had to change makeRequest call to be a POST.

* Had to use java_stream_to_string instead of copy_java_stream_to_io. Not
  ideal, since it will not work well for binary data. In this case, it
  is alright.
Use admin layout for OAutH provider pages.