Add Cloudstack snitch

Patch by Pierre-Yves Ritschard, reviewed by brandonwilliams for
CASSANDRA-7147
Merge branch 'cassandra-1.2' into cassandra-2.0
Add Cloudstack snitch

Patch by Pierre-Yves Ritschard, reviewed by brandonwilliams for
CASSANDRA-7147
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
Merge branch 'cassandra-2.1' into trunk