Restore expiring->deleted (cell) compaction optimization

patch by Aleksey Yeschenko; reviewed by Sylvain Lebresne for
CASSANDRA-6844
fixed bug in CompactionManager.needsCleanup

Patch by Dmitrij Koniajev, reviewed by marcuse for CASSANDRA-6845.
Correctly compare BooleanType values other than 0 and 1

Patch by Sylvain Lebresne, reviewed by Tyler Hobbs for CASSANDRA-6779
add #2635 to CHANGES
Merge branch 'cassandra-1.2' into cassandra-2.0
fix nodetool getsstables for blob PK
patch by Nate McCall; reviewed by jbellis for CASSANDRA-6803
merge from 1.2
Fix leaking validator FH in StreamWriter
patch by Joshua McKenzie; reviewed by jbellis for CASSANDRA-6832
Load a truststore if client certificate authentication is enabled

patch by Mikhail Stepura; reviewed by Jason Brown for CASSANDRA-6847
Merge branch 'cassandra-1.2' into cassandra-2.0
Delimiter not working for special characters in COPY command from CQLSH

patch by Shiti Saxena; reviewed by Mikhail Stepura for CASSANDRA-6773
Merge branch 'cassandra-1.2' into cassandra-2.0
Ninja-commit for "Add LZ4Compressor in CQL document" CASSANDRA-6331
fix duplicate classes between cassandra-all and cassandra-thrift

patch by dbrosius reviewed by jbellis for CASSANDRA-5833
Read message id as string from older nodes.

Patch by marcuse, reviewed by jbellis for CASSANDRA-6840
Fix schema concurrency exceptions
patch by Benedict Elliott Smith; reviewed by Carl Yeksigian for CASSANDRA-6841
Fix failing pig test

Patch by Alex Liu, reviewed by brandonwilliams for CASSANDRA-6376
Merge branch 'cassandra-1.2' into cassandra-2.0
Fix truncate to not abort due to unreachable fat clients
patch by Oleg Anastasyev; reviewed by jbellis for CASSANDRA-6864
Merge remote-tracking branch 'origin/cassandra-2.0' into cassandra-2.0