Application prefs section (#2758)

* Add code for creating/managing apps to settings section

* Add specs for app changes

* Fix controller spec

* Fix view file I pasted over by mistake

* Add locale strings. Add 'my apps' to nav

* Add Client ID/Secret to App page. Add some visual separation

* Fix rubocop warnings

* Fix embarrassing typo

I lost an `end` statement while fixing a merge conflict.

* Add code for creating/managing apps to settings section

- Add specs for app changes
- Add locale strings. Add 'my apps' to nav
- Add Client ID/Secret to App page. Add some visual separation
- Fix some bugs/warnings

* Update to match code standards

* Trigger notification

* Add warning about not sharing API secrets

* Tweak spec a bit

* Cleanup fixture creation by using let!

* Remove unused key

* Add foreign key for application<->user

config/initializers/doorkeeper.rb

@@ -50,7 +50,7 @@ Doorkeeper.configure do
   # Optional parameter :confirmation => true (default false) if you want to enforce ownership of
   # a registered application
   # Note: you must also run the rails g doorkeeper:application_owner generator to provide the necessary support
-  # enable_application_owner :confirmation => true
+  enable_application_owner
 
   # Define access token scopes for your provider
   # For more information go to