Auto reload GossipingPropertyFileSnitch config

Patch by Danield Shelepov, reviewed by Tyler Hobbs for CASSANDRA-5897
Fix potentially repairing with wrong nodes

patch by yukim; reviewed by krummas for CASSANDRA-6808
Fix HSHA server introducing corrupt data

patch by xedin; reviewed by slebresne for CASSANDRA-6285
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
Fix CAS conditions for COMPACT STORAGE tables

patch by slebresne; reviewed by iamaleksey for CASSANDRA-6813
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
	src/java/org/apache/cassandra/cql3/ColumnCondition.java
	src/java/org/apache/cassandra/cql3/statements/CQL3CasConditions.java
Merge remote-tracking branch 'origin/cassandra-2.1' into iss-6689-1
remove GC state from PoolAllocator