pass specific Gson, and cast Json Object to specific POJO

[mohammed-eladly-afaqy]

Create Gson Object with special De/Serializer, and register Adapters,

cast returned object from type Object to a specific POJO object {ex, Person ,MyObject, ..etc..}

[gkorland]

@mohammed-eladly-afaqy thanks for you PR. Please see if it's still relevant once #16 was merged.