Randomize batchlog candidates selection

patch by Aleksey Yeschenko; reviewed by Jonathan Ellis for
CASSANDRA-6481
Set javaagent for tools.
Patch by Sam Tunnecliffe, reviewed by brandonwilliams for CASSANDRA-6404
Fix CHANGES.txt
Pig: don't assume all DataBags are DefaultDataBags
Patch by Mike Spertus, reviewed by brandonwilliams for CASSANDRA-6420
fix race referencing tokenMetadataCache
patch by jbellis; reviewed by rbranson for CASSANDRA-6485
Improve batchlog write performance with vnodes

patch by Jonathan Ellis and Rick Branson; reviewed by Aleksey Yeschenko
for CASSANDRA-6488
Slightly improved message when parsing properties for DDL queries

patch by boneill42; reviewed by slebresne for CASSANDRA-6453
caching all calls of cloneOnlyTokenMap is not correct since many callers mutate the result
patch by Aleksey Yeschenko; reviewed by jbellis for CASSANDRA-6488
Simplify TokenMetadata.cachedOnlyTokenMap()
ninja-correcting the the constant for LOCAL_ONE.
Allow executing CREATE statement multiple times

patch by slebresne; reviewed by jbellis for CASSANDRA-6471
Don't send confusing info on timeouts

patch by slebresne; reviewed by jbellis for CASSANDRA-6491
Don't drop local mutations without a trace

patch by Aleksey Yeschenko; reviewed by Jonathan Ellis for
CASSANDRA-6510
Don't allow null max_hint_window_in_ms
patch by Nate McCall; reviewed by jbellis for CASSANDRA-6419