Support protocol init

[Xioshock]

Hey, nice library. It would by nice if it also supported protocols (with implementation) instead of just subclassing. Some other libraries, mainly ORMs need subclassing and it would be impossible to use this and Realm for example, or even SharkORM, at the same time.

[johnlui]

Thanks for your feedback!

I know sub-class method is not a good one when using swift, and it is not swifty at all. But if I want to build the auto-reflection feature, I really need OC runtime.

Sorry.