Skip validations in the oauth migration

Also enforced the presence of needed attributes of the services table on
the database level

app/concerns/oauthable.rb

@@ -4,7 +4,6 @@ module Oauthable
   included do |base|
     attr_accessible :service_id
     validates_presence_of :service_id
-    base.extend ClassMethods
     self.class_variable_set(:@@valid_oauth_providers, :all)
   end
 

db/migrate/20140515211100_create_services.rb

@@ -1,10 +1,10 @@
 class CreateServices < ActiveRecord::Migration
   def change
     create_table :services do |t|
-      t.integer :user_id
-      t.string :provider
-      t.string :name
-      t.text :token
+      t.integer :user_id, null: false
+      t.string :provider, null: false
+      t.string :name, null: false
+      t.text :token, null: false
       t.text :secret
       t.text :refresh_token
       t.datetime :expires_at

db/migrate/20140525150140_migrate_agents_to_service_authentication.rb

@@ -24,7 +24,7 @@ class MigrateAgentsToServiceAuthentication < ActiveRecord::Migration
         secret: twitter_oauth_token_secret(agent)
       )
       agent.service_id = service.id
-      agent.save!
+      agent.save!(validate: false)
     end
     if agents.length > 0
       puts <<-EOF.strip_heredoc