make sure factory_girl is loaded for specs

Some specs behave depending on the version of FactoryGirl. On Travis,
specs see < 2.0, but the implementation sees 2.0 (presence of
::FactoryGirl)

spec/spec_helper.rb

@@ -2,6 +2,7 @@
 require 'rspec'
 require 'active_support'
 require 'active_record'
+require 'factory_girl'
 
 $:.unshift(File.dirname(__FILE__) + '/../lib')
 require 'pickle'