Avoid IAE in IndexSummaryManager while sorting sstables

Patch by Tyler Hobbs; reviewed by Benjamin Lerer for CASSANDRA-8182
Merge branch 'cassandra-2.1' into trunk
Merge remote-tracking branch 'origin/trunk' into 7813-udf-keyspace
Handle negative timestamps in writetime method

patch by slebresne; reviewed by thobbs for CASSANDRA-8139
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
	src/java/org/apache/cassandra/cql3/UpdateParameters.java
Merge branch 'cassandra-2.1' into trunk

Conflicts:
	src/java/org/apache/cassandra/cql3/statements/Selection.java
Fix race in RecoveryManagerTest
patch by Sam Tunnicliffe; reviewed by jbellis for CASSANDRA-8176
merge from 2.1
Update CQLSSTableWriter to allow parallel writing of SSTables on the same table within the same JVM

Patch by Carl Yeksigian, reviewed by Benjamin Lerer for CASSANDRA-7463
Merge branch 'cassandra-2.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
Merge remote-tracking branch 'origin/trunk' into 7813-udf-keyspace
more review stuff