add describe_local_ring for Hadoop's benefit
patch by Piotr Kołaczkowski; reviewed by jbellis for CASSANDRA-6268
Don't resubmit counter mutation runnables internally

patch by Aleksey Yeschenko; reviewed by Jonathan Ellis for
CASSANDRA-6427
Merge branch 'cassandra-2.0' into trunk
Merge branch 'cassandra-1.2' into cassandra-2.0
Merge branch 'cassandra-2.0' into trunk
Fix handling of concurrent directory creation failure

patch by Ryan Fowler; reviewed by Aleksey Yeschenko for
CASSANDRA-6459
Merge branch 'cassandra-1.2' into cassandra-2.0
Merge branch 'cassandra-2.0' into trunk
Fix test build
Merge branch 'cassandra-1.2' into cassandra-2.0
Merge branch 'cassandra-2.0' into trunk
remove dead fields