Fix tracing on the new SEPExecutor
patch by jbellis; reviewed by bes for CASSANDRA-7644
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1.0' into trunk
Filter cached results correctly.

Patch by marcuse, reviewed aleksey for CASSANDRA-7636
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk