Improve error message when trying >= 2.0 on java < 1.7

Patch by brandonwilliams reviewed by thobbs for CASSANDRA-7137
Remove unused isLocalTask method.

Patch by Lyuben Todorov, reviewed by brandonwilliams for CASSANDRA-7181
return all cpu values from BackgroundActivityMonitor.readAndCompute

patch by dbrosius reviewed by jbellis for cassandra-7183
reduce garbage creation in calculatePendingRanges

patch by dbrosius reviewed by bwilliams for cassandra-7191
Merge branch 'cassandra-1.2' into cassandra-2.0
fix c* launch issues on Russian os's due to output of linux 'free' cmd

patch by dbrosius reviewed by bwilliams for cassandra-6162
Check if autocompaction should be disabled before enabling it during startup.

Patch by marcuse; reviewed by driftx for CASSANDRA-7187
Fix potential NumberFormatException when deserializing IntegerType

patch by slebresne; reviewed by jbellis for CASSANDRA-7088
cqlsh should return a non-zero error code if a query fails

patch by Branden Visser and Mikhail Stepura; reviewed by Mikhail Stepura for CASSANDRA-6344
Merge branch 'cassandra-1.2' into cassandra-2.0

Conflicts:
	bin/cqlsh
CQLSH: adjusted compaction_strategy_options with the latest docs

patch by Mikhail Stepura; reviewed by Brandon Williams for CASSANDRA-7185
Ninja: add missing "enabled" option to compaction options docs

Done for CASSANDRA-7185
Fix potential SlabAllocator yield-starvation
patch by bes; reviewed by jbellis for CASSANDRA-7133
cqlsh: Accept and execute CQL statement(s) from command-line parameter

patch by Mikhail Stepura; reviewed by Brandon Williams for CASSANDRA-7172
Make StreamSession more thread safe

patch by sankalp kohli; reviewed by yukim for CASSANDRA-7092
Fix IllegalStateException in CqlPagingRecordReader for inputPageRowSize

patch by btheisen reviewed by dbrosius for cassandra-7198
Quiet the unsafe use warning during build
Fix the InvertedIndex trigger example

patch by Anthony Cozzie; reviewed by Aleksey Yeschenko for CASSANDRA-7211
Close java driver Cluster in CQLRR.close
patch by Mariusz Kryński; reviewed by jbellis for CASSANDRA-7228
Exclude xerces to fix hadoop build issue.

Patch by Sam Tunnicliffe, reviewed by brandonwilliams for CASSANDRA-6877