do not ignore user configured JAVA_HOME

Patch by eevans; reviewed by Michael Shuler for CASSANDRA-6131
Move *PropDefs to o.a.c.cql3.statements
Add ability to throttle batchlog replay

patch by Aleksey Yeschenko; reviewed by Jonathan Ellis for
CASSANDRA-6550
Merge branch 'cassandra-1.2' into cassandra-2.0

Conflicts:
	NEWS.txt
	src/java/org/apache/cassandra/db/BatchlogManager.java
6505: Backport global shards
6505: Tests for CounterContext changes