RFObjectPool refactoring as mentioned in #43.

RFObjectPool refactoring as mentioned in #43.
NSDateFormatter local pool realizations are removed from coders/decoders in ROADSerialization and replaced with RFObjectPool.
Not sure that I completely caught a point. I supposed a pool could be parametrized by the type of the objects it stores, and in that case we can create and init objects automatically. If the type of stored object is not provided, we do not able neither create nor init object right in the pool, but can store objects of any type in it instead. The RFObjectPoolDefaultInitializerBlock is intended to replace a delegate for such an automatic initialization of the new objects created.