Fix failing tests for edge rails

 * Edge Rails returns an instance of 'Gem::Version' for 'Rails.version' due to e600384515dc06db2c56ff5be5c18779f7b379a5
 * Travis build was failing because of this as 'Rails.version.start_with? '4'' was giving 'undefined method' on 'Gem::Version' instance
Merge pull request #256 from prathamesh-sonpatki/edge_rails_failing_test

Fix failing tests for edge rails