Specify base controller for Doorkeeper

This will make sure the `ApplicantionController#can?` method is
available for views rendering menus based on the current user's abilities.

config/initializers/doorkeeper.rb

@@ -103,4 +103,6 @@ Doorkeeper.configure do
   # Some applications require dynamic query parameters on their request_uri
   # set to true if you want this to be allowed
   # wildcard_redirect_uri false
+
+  base_controller 'ApplicationController'
 end

spec/controllers/oauth/authorizations_controller_spec.rb

@@ -34,6 +34,8 @@ describe Oauth::AuthorizationsController do
     end
 
     context 'with valid params' do
+      render_views
+
       it 'returns 200 code and renders view' do
         get :new, params