Implement role authorization

app/models/role.rb

@@ -1,4 +1,10 @@
 class Role < ActiveRecord::Base
-  attr_accessible :name
+  attr_accessible :name, :description
   has_and_belongs_to_many :users
+  belongs_to :resource, polymorphic: true
+
+  scopify
+
+  LABELS = ['Attendee', 'Volunteer', 'Speaker', 'Sponsor', 'Press', 'Keynote Speaker']
+  ACTIONABLES = ['Organizer', 'CfP', 'Info Desk', 'Volunteers Coordinator']
 end