Pass the updated cf to the PRSI index() method

patch by Ben Coverston; reviewed by Aleksey Yeschenko for
CASSANDRA-5999
Merge branch 'cassandra-1.2' into cassandra-2.0

Conflicts:
	src/java/org/apache/cassandra/db/index/PerRowSecondaryIndex.java
	src/java/org/apache/cassandra/db/index/SecondaryIndexManager.java
Merge branch 'cassandra-2.0' into trunk