Update ConferenceRegistrationsController#new

- authenticate on all controller actions unless (OSEM_ICHAIN_ENABLED != true and
  action is 'new' or 'create')

- before_filter rename to before_action

- addition of before_action :user_already_registered on :new action (redirects
  to edit if user already registered)

- increased specs

app/models/ability.rb

@@ -45,16 +45,17 @@ class Ability
     # can view Commercials of confirmed Events
     can :show, Commercial, commercialable_type: 'Event', commercialable_id: Event.where(state: 'confirmed').pluck(:id)
     can [:show, :create], User
+
+    can [:new, :create], Registration do |registration|
+      conference = registration.conference
+      conference.registration_open? && registration.new_record? && !conference.registration_limit_exceeded?
+    end
+
     unless ENV['OSEM_ICHAIN_ENABLED'] == 'true'
       can :show, Registration do |registration|
         registration.new_record?
       end
 
-      can [:new, :create], Registration do |registration|
-        conference = registration.conference
-        conference.registration_open? && registration.new_record? && !conference.registration_limit_exceeded?
-      end
-
       can :show, Event do |event|
         event.new_record?
       end
@@ -74,11 +75,6 @@ class Ability
 
     can :manage, Registration, user_id: user.id
 
-    can [:new, :create], Registration do |registration|
-      conference = registration.conference
-      conference.registration_open? && !conference.registration_limit_exceeded?
-    end
-
     can :index, Ticket
     can :manage, TicketPurchase, user_id: user.id
     can [:new, :create], Payment, user_id: user.id