Expose off-heap memory usage stats

patch by Benjamin Lerer; reviewed by Aleksey Yeschenko for
CASSANDRA-7897
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
	src/java/org/apache/cassandra/io/sstable/SSTableReader.java
	src/java/org/apache/cassandra/tools/NodeCmd.java
	src/java/org/apache/cassandra/utils/IFilter.java
	src/java/org/apache/cassandra/utils/obs/IBitSet.java
Merge branch 'cassandra-2.1' into trunk
Fix CQLTester

patch by snazy; reviewed by blerer for CASSANDRA-8392
use parameterized logging
don't declare throwing exceptions that aren't
use try-with-resources
Fixed typo

Patch by davedamoon; reviewed by marcuse for CASSANDRA-8395
Merge branch 'cassandra-2.1' into trunk
Merge remote-tracking branch 'origin/trunk' into 8053-udaf-v2