Include correct consistencyLevel in LWT timeout
patch by Sankalp Kohli; reviewed by jbellis for CASSANDRA-6884
merge from 2.0
Merge remote-tracking branch 'origin/cassandra-2.1' into cassandra-2.1
Omit tombstones from schema digests
patch by Oleg Anastasyev; reviewed by jbellis for CASSANDRA-6862
merge from 2.0