Fix authorization of new and create in ConferenceRegistrationsController

Before authorization we need to set conference relation.
Change in proposal spec cause conference has to have valid registration
period for successful redirect to registration after confirm proposal.

app/models/ability.rb

@@ -46,9 +46,13 @@ class Ability
     can :show, Commercial, commercialable_type: 'Event', commercialable_id: Event.where(state: 'confirmed').pluck(:id)
     can :show, User
     unless CONFIG['authentication']['ichain']['enabled']
-      can [:show, :create], Registration do |registration|
+      can :show, Registration do |registration|
         registration.new_record?
       end
+
+      can [:new, :create], Registration do |registration|
+        registration.conference.registration_open? && registration.new_record?
+      end
       can :show, Event do |event|
         event.new_record?
       end