Remove consumer_id from session

* Each external (and also internal) user has a consumer attached. We don't need that information twice.

spec/controllers/sessions_controller_spec.rb

@@ -200,7 +200,6 @@ describe SessionsController do
 
     before(:each) do
       #Todo replace session with lti_parameter
-      session[:consumer_id] = consumer.id
       #Todo create LtiParameter Object
       # session[:lti_parameters] = {}
     end