CassandraCounterBatchingBolt takes Type parameters

This allows CassandraCounterBatchingBolt to write to rows that have
rowkeys with a type other than string.

Had also to correct the TupleCounterMapper and the Astyanax client.

The DefaultTupleCounterMaper uses String for rowkeys and columnkeys.

Corrected the CassandraBoltTest to work with this alterations.