Added/Tested:
* PredictionIO::AsyncIO
* PredictionIO::Configurator
* PredictionIO::Worker
* PredictionIO::Rescuer
* PredictionIO::Logger
* A file in lib/prediction_io called load to load all the objects
it needs to work.

DONE:
  Refactored all tests and objects

Removed:
* PredictionIO::AsyncConsumer as it was not the right design.

TODO:
  Finish User implementation ( extract them and test )
  Finish Server implementation