Fix validation of indexes on composite column components of COMPACT tables

patch by slebresne; reviewed by thobbs for CASSANDRA-8156
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	CHANGES.txt
	src/java/org/apache/cassandra/cql3/statements/CreateIndexStatement.java
Merge branch 'cassandra-2.1' into trunk