Fix connection problems with fetching token ranges from hosts with rpc_address different than listen_address.

Use rpc_endpoints instead of endpoints in CassandraRDDPartitioner.
Log host address(es) and ports on connection failures.
Close thrift transport if connection fails for some reason after opening the transport, e.g. authentication failure.

Fixes #304.
Merge branch 'wip-304-failed-to-fetch-splits' into b1.0

Conflicts:
	CHANGES.txt