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

db/schema.rb

@@ -216,8 +216,11 @@ ActiveRecord::Schema.define(version: 20170720000000) do
     t.string "scopes", default: "", null: false
     t.datetime "created_at"
     t.datetime "updated_at"
-    t.boolean "superapp", default: false, null: false
-    t.string "website"
+    t.boolean  "superapp",     default: false, null: false
+    t.string   "website"
+    t.integer  "owner_id"
+    t.string   "owner_type"
+    t.index ["owner_id", "owner_type"], name: "index_oauth_applications_on_owner_id_and_owner_type", using: :btree
     t.index ["uid"], name: "index_oauth_applications_on_uid", unique: true
   end