Add property to disable stcs in L0

Patch by marcuse; reviewed by tjake for CASSANDRA-6621
Merge branch 'cassandra-2.0' into cassandra-2.1.0

Conflicts:
	CHANGES.txt
	NEWS.txt
	src/java/org/apache/cassandra/db/compaction/LeveledManifest.java
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
Remove left-over rows_per_partition_to_cache

Patch by marcuse; reviewed by jbellis for CASSANDRA-7493
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
Remove left-over populate_io_cache_on_flush and replicate_on_write uses

patch by Aleksey Yeschenko; reviewed by Jonathan Ellis for CASSANDRA-7493
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk

Conflicts:
	doc/cql/CQL.textile
	src/java/org/apache/cassandra/cql/CFPropDefs.java
Add conf/hotspot_compiler to .gitignore
Merge branch 'cassandra-2.1' into trunk
Fix prepared marker for collections inside UDT
patch by slebresne; reviewed by thobbs for CASSANDRA-7472
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk
Fix ClassCastException processing expired messages
patch by Jason Brown; reviewed by tjake for CASSANDRA-7496
Workaround JVM NPE on JMX bind failure
patch by Brandon Williams; reviewed by tjake for CASSANDRA-7254
merge from 2.0
Merge branch 'cassandra-2.1.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk