Add metrics to track usage of PreparedStatments

patch by tjake; reviewed by carl for (CASSANDRA-7719)
Merge branch 'cassandra-2.1' into trunk
ninja fix test
Merge branch 'cassandra-2.1' into trunk
Update Xss in test/cassandra.in.sh

Done for CASSANDRA-7856
Merge branch 'cassandra-2.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
cassandra-stress: merge 7468 into 2.1, and ninja-fix duration setting for user command
Merge branch 'cassandra-2.1' into trunk
cassandra-stress: ninja fix profile param for user command to required, and print required fields first
Merge branch 'cassandra-2.1' into trunk
Don't use _ as a reference
Merge branch 'trunk' of https://git-wip-us.apache.org/repos/asf/cassandra into trunk
remove unneeded override
Allow pid file to be read by mere mortals.

Patch by Michael Shuler, reviewed by brandonwilliams for CASSANDRA-7851
Merge branch 'cassandra-2.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
Fix yaml snitch reconnect trick

Patch by Holger Bornträger, reviewed by brandonwilliams for CASSANDRA-7912
Merge branch 'cassandra-2.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk