Add back ColumnIdentifier comparison since we do use it
Merge branch 'cassandra-1.2' into cassandra-2.0

Conflicts:
	src/java/org/apache/cassandra/cql3/CFDefinition.java
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	src/java/org/apache/cassandra/cql3/CFDefinition.java
Ninja-fix RefCountedMemory
Merge branch 'cassandra-2.1' into trunk