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
deprecate yaml snitch
Merge branch 'cassandra-2.1' into trunk
kill yaml snitch
Fix CHANGES.txt
Merge branch 'cassandra-2.1' into trunk
Merge remote-tracking branch 'origin/trunk' into 7769-pg-style-string
Dont try to set repairedAt on old sstables

Patch by marcuse; reviewed by jbellis for CASSANDRA-7913
Merge branch 'cassandra-2.1' into trunk
update changes/news for 7917
Add human readable option to nodetool outputs.

Patch by Michael Nelson, reviewed by brandonwilliams for CASSANDRA-5433
Merge branch 'cassandra-2.1' into trunk
Consistently name get/set trace probability JMX calls.

Patch by Nitzan Volman, reviewed by brandonwilliams for CASSANDRA-6926
Don't try to shutdown client servers if they don't exist.

Patch by Steve Nelson, reviewed by brandonwilliams for CASSANDRA-7889
Merge branch 'cassandra-2.0' into cassandra-2.1