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

spec/models/user_spec.rb

@@ -286,4 +286,24 @@ RSpec.describe User, type: :model do
       Fabricate(:user)
     end
   end
+
+  describe 'token_for_app' do
+    let(:user) { Fabricate(:user) }
+    let(:app) { Fabricate(:application, owner: user) }
+
+    it 'returns a token' do
+      expect(user.token_for_app(app)).to be_a(Doorkeeper::AccessToken)
+    end
+
+    it 'persists a token' do
+      t = user.token_for_app(app)
+      expect(user.token_for_app(app)).to eql(t)
+    end
+
+    it 'is nil if user does not own app' do
+      app.update!(owner: nil)
+
+      expect(user.token_for_app(app)).to be_nil
+    end
+  end
 end