initial CAS support
patch by jbellis and slebresne for CASSANDRA-5062
Merge branch 'cassandra-1.2' into trunk

Conflicts:
	src/java/org/apache/cassandra/db/ColumnIndex.java
	src/java/org/apache/cassandra/io/sstable/SSTableWriter.java
	test/unit/org/apache/cassandra/streaming/StreamingTransferTest.java
fix merge failure
remove PBSPredictor
patch by jbellis; reviewed by marcuse for CASSANDRA-5455
Avoid serializing keyspace redundantly in RowMutation
patch by jbellis; reviewed by vijay for CASSANDRA-5458
fix SerializationsTest
make CompositesIndex.IndexEntry static to reduce footprint
Merge branch 'cassandra-1.2' into trunk
Merge branch 'cassandra-1.2' into trunk
Merge branch 'cassandra-1.2' into trunk
Merge branch 'cassandra-1.2' into trunk
Merge branch 'cassandra-1.2' into trunk
comments
Merge branch 'cassandra-1.2' into trunk
Merge branch 'cassandra-1.2' into trunk
Merge branch 'cassandra-1.2' into trunk
Merge branch 'cassandra-1.2' into trunk
Merge branch 'cassandra-1.2' into trunk
Merge branch 'cassandra-1.2' into trunk
assert