Refactor to change purpose of the S3Emitter class

[aldemirenes]

Right now, all methods for sending data to S3 are in the S3Emitter class which is only used with Kinesis. It will be good if we refactor this class to make that it can be used with other tools such as NSQ too and create new KinesisS3Emitter class for sending data to S3 from Kinesis.