Add support for counter and logger batches and minor fix to cass_cluster_connect_keyspace

I needed counter batches for testing the driver and while BatchRequest has support for type, it was not available in the api. The patch adds a second version of cass_batch_new which supports additional type parameter:

CASS_EXPORT CassBatch*
cass_batch_new2(CassConsistency consistency, CassBatchType type);

The second fix makes cass_cluster_connect_keyspace use the provided keyspace parameter instead of an empty string.