Big refactoring of registration

- Added datatable gem
- Addaed datatable to events, users (#422), registrations

app/models/conference.rb

@@ -26,7 +26,7 @@ class Conference < ActiveRecord::Base
 
   has_paper_trail
 
-  has_and_belongs_to_many :questions
+  has_many :questions
 
   has_one :contact, dependent: :destroy
   has_one :registration_period, dependent: :destroy

app/models/registration.rb

@@ -28,6 +28,8 @@ class Registration < ActiveRecord::Base
 
   alias_attribute :other_needs, :other_special_needs
 
+  validates_uniqueness_of :user_id, scope: :conference_id, message: 'already Registered!'
+
   after_create :set_week
 
   def week

app/models/subscription.rb

@@ -3,4 +3,6 @@ class Subscription < ActiveRecord::Base
   validates_uniqueness_of :user_id, scope: [:conference_id]
   belongs_to :conference
   belongs_to :user
+
+  validates_uniqueness_of :user_id, scope: :conference_id, message: 'already subscribed!'
 end

app/models/user.rb

@@ -16,7 +16,8 @@ class User < ActiveRecord::Base
   has_many :openids
 
   attr_accessible :email, :password, :password_confirmation, :remember_me, :role_id, :role_ids,
-                  :name, :email_public, :biography, :nickname, :affiliation, :is_admin
+                  :name, :email_public, :biography, :nickname, :affiliation, :is_admin,
+                  :tshirt, :mobile, :volunteer_experience, :languages
 
   has_many :event_users, dependent: :destroy
   has_many :events, -> { uniq }, through: :event_users