Remove unused (and slightly broken) ColumnIdentifier.compareTo
Merge branch 'cassandra-1.2' into cassandra-2.0

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

Conflicts:
	src/java/org/apache/cassandra/cql3/ColumnIdentifier.java