Handle AccessDenied in management sessions

We were raising a `CanCan::AcessDenied` and were getting a 500 Internal
Server Error.

I've chosen to do the same thing we do in the ApplicationController.
There are other options to handle this request, like redirecting to the
login page or returning a 401 Unauthorized HTTP status.

app/controllers/application_controller.rb

@@ -3,6 +3,7 @@ require "application_responder"
 class ApplicationController < ActionController::Base
   include HasFilters
   include HasOrders
+  include AccessDeniedHandler
 
   protect_from_forgery with: :exception
 
@@ -17,13 +18,6 @@ class ApplicationController < ActionController::Base
   check_authorization unless: :devise_controller?
   self.responder = ApplicationResponder
 
-  rescue_from CanCan::AccessDenied do |exception|
-    respond_to do |format|
-      format.html { redirect_to main_app.root_url, alert: exception.message }
-      format.json { render json: {error: exception.message}, status: :forbidden }
-    end
-  end
-
   layout :set_layout
   respond_to :html
   helper_method :current_budget