Setup basic Revision History page

Sets up paper_trail tracking in important models

and add conference_id to versions for storing conference_id
of conference related objects  as metadata.This will help in querying
for versions related to conferences.

Fix issues with factories & event types initialization.Import paper_trail testing helpers
Fix bug: Creating an event creates a useless version with event update

Add revert and view changes features to revision history

app/models/room.rb

@@ -2,6 +2,8 @@ class Room < ActiveRecord::Base
   belongs_to :venue
   has_many :event_schedules, dependent: :nullify
 
+  has_paper_trail ignore: [:guid], meta: { conference_id: :conference_id }
+
   before_create :generate_guid
 
   validates :name, :venue_id, presence: true
@@ -14,4 +16,8 @@ class Room < ActiveRecord::Base
     guid = SecureRandom.urlsafe_base64
     self.guid = guid
   end
+
+  def conference_id
+    venue.conference_id
+  end
 end