Pick the correct value validator in sstable2json for CQL3

patch by slebresne; reviewed by driftx for CASSANDRA-5134
Fix CQL3 doc
Add jmx/nodetool methods to enable/disable hint storage/delivery
Patch by Alexey Zotov and brandonwilliams, reviewed by Alexey Zotov for
CASSANDRA-4750
Merge branch 'cassandra-1.2' into trunk

Conflicts:
	src/java/org/apache/cassandra/db/HintedHandOffManager.java