Native types refactoring

Okay, here's next step in making EasyMapping better =) Things in this PR:

1. Refactored native types mapping and serialization.
2. Array introspection moved to EKPropertyHelper. It should be the only class, that needs access to objc/runtime. 
3. Fixed 2 failing tests for 64 bit architecture.

Special thanks to @advantis for property type introspection, seems like a very dark magic to me. 

/cc @lucasmedeirosleite This will probably be my last PR for this weekend, need some time to rest =)) Next step would probably be building benchmark for speed measures. But i'll probably will not start working on it until next weekend.