Fix SSTable not released if stream session fails

patch by yukim; reviewed by Richard Low for CASSANDRA-6818
Merge branch 'cassandra-2.0' into cassandra-2.1
fix test compile
if relocate is a no-op, don't try to op.
Merge branch 'cassandra-1.2' into cassandra-2.0
Merge branch 'cassandra-2.0' into cassandra-2.1
Revert "Fix LatencyMetrics returning infinity."

This reverts commit 5e51aa4e6d1d868bb82a1aa2ffaed4613b24ffc1.
getRecentLatency returns zero instead of infinity

Patch by Benedict, reviewed by brandonwilliams for CASSANDRA-6920
Merge branch 'cassandra-2.0' into cassandra-2.1
Track presence of legacy counter shards in sstables

patch by Aleksey Yeschenko; reviewed by Marcus Eriksson for
CASSANDRA-6888
Ensure safe resource cleanup when replacing SSTables

Patch by belliotsmith; reviewed by Tyler Hobbs for CASSANDRA-6912
Make sure we clear out all levels when rebuilding leveled manifest.

Patch by jbellis; reviewed by marcuse for CASSANDRA-6957
Don't shut MessagingService down.

Patch by brandonwilliams, reviewed by Benedict for CASSANDRA-6948
Merge branch 'cassandra-2.0' into cassandra-2.1
Avoid build failure due to ANTLR timeout

Patch by Ben Chan; reviewed by Tyler Hobbs for CASSANDRA-6991
Merge branch 'cassandra-2.0' into cassandra-2.1
Fix NPE caused by CASSANDRA-6818

patch by yukim; reviewed by thobbs for CASSANDRA-6984
Merge branch 'cassandra-2.0' into cassandra-2.1
Schedule schema pull in onChange.

Patch by brandonwilliams, reviewed by Russ Hatch for CASSANDRA-6971
Merge branch 'cassandra-1.2' into cassandra-2.0