export MALLOC_ARENA_MAX corrrectly

Patch by brandonwilliams, reviewed by jbellis for CASSANDRA-6126
Merge branch 'cassandra-2.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
Add new CMS GC flags on Windows launch scripts for JVM > 7u60

Patch by Josh McKenzie, reviewed by jbellis for CASSANDRA-7714
Merge branch 'cassandra-2.1' into trunk
Merge remote-tracking branch 'origin/trunk' into 7562-udf-java