Rails 4 fix

Overriding core extensions provided by rails such as try can create compatibility problems with new versions of rails.

Case in point, rails 4.0.0.beta1 and grape-swagger master. Grape swagger master was overriding try on object which resulted in a fixnum? message being sent to an object erroneously. Upgrading the definition of try to that included in activesupport 4.0.0.beta1 fixed this but I have also moved the method definitions to avoid further problems.