Fix NPE in StreamTransferTask.createMessageForRetry()

patch by Josh McKenzie; reviewed by Aleksey Yeschenko for CASSANDRA-7323
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
make Shuffle client static
Merge branch 'cassandra-2.0' into cassandra-2.1
Upgrade to Pig 0.12.1

Patch by brandonwilliams for CASSANDRA-6556
fix cast guard to be of the c* FutureTask type
use long math for long results
Make StreamSession#closeSession() idempotent

Patch by JoshuaMcKenzie; reviewed by marcuse for CASSANDRA-7262
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
remove incorrect use of generics in non-generified method call
Merge branch 'cassandra-2.0' into cassandra-2.1
make NoOp's constructor private as it's a singleton
Fix infinite loop on exception while streaming

Patch by JoshuaMcKenzie; reviewed by marcuse for CASSANDRA-7330
Merge branch 'cassandra-2.0' into cassandra-2.1
Make sure we clear out repair sessions from netstats

Patch by JoshuaMcKenzie; reviewed by marcuse for CASSANDRA-7329
Don't fail streams on failure detector downs

Patch by JoshuaMcKenzie; reviewed by marcuse for CASSANDRA-3569
Add missing file
merge #7063 from 1.2
Merge branch 'cassandra-2.0' into cassandra-2.1
Fix handling of empty counter replication mutations

patch by Aleksey Yeschenko; reviewed by Richard Low for CASSANDRA-7144