Improve memory usage of metadata min/max column names
patch by Oleg Anastasyev; reviewed by jbellis for CASSANDRA-6077
Move batchlog replay to its own executor
patch by Oleg Anastasyev; reviewed by jbellis for CASSANDRA-6079
backport CASSANDRA-6079
CHANGES
Merge branch 'cassandra-1.2' into cassandra-2.0
merge from 1.2