Support for Rubymotion

The NSDictionary that rubymotion creates from hashes doesn't seem to gel well with `indexOfObjectIdenticalTo`, perhaps something to do with the way constants are handled? This change allows CRToast to be used with rubymotion while keeping the valid key checking intact.
Merge pull request #86 from balvig/rubymotion

Fix for Rubymotion, removed use of `indexOfObjectIdenticalTo:`