Implement better transaction codecs

The current codec simply uses Thrift. However, with large invalid lists, the encoded byte array cvan become very large, Using compression techniques such as delta encoding, variable length integer encoding, or simple compression can greatly reduce the size of the encoded byte array, as well as the time it takes to encode, transmit, and decode the transaction.

This can be applied to the transactions in the Thrift protocol as well as to the transactions that are attached to the HBase operations.