Fix concurrency issue for CASSANDRA-6818

patch by yukim; reviewed by thobbs for CASSANDRA-7007
Merge branch 'cassandra-2.0' into cassandra-2.1
Put nodes into hibernate when join_ring is false.

Patch by brandonwilliams, reviewed by Tyler Hobbs for CASSANDRA-6961
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	src/java/org/apache/cassandra/service/StorageService.java