Fix race in Thrift server that can exhaust the pool of worker threads
patch by Christian Rolf and jbellis for CASSANDRA-6788
Merge branch 'cassandra-1.2' into cassandra-2.0
Ninja-fix counter-in-primary-key validation exception message
Merge branch 'cassandra-1.2' into cassandra-2.0

Conflicts:
	src/java/org/apache/cassandra/cql3/statements/CreateTableStatement.java
Merge branch 'cassandra-2.0' into cassandra-2.1