Make it compile with Hadoop CDH4

Needed when we want to use Hadoop CDH4 (2.0) mrv1/mrv2 over Cassandra

Conflicts:
	build.xml
revert default read/write consistency level to ONE to be compatible with 2.0.1 server
Naive approach to preventing duplicate fields in CqlStorage.getColumnMetadata
Support a bag of KeyValue tuples for Maps as well as a Tuple of Tuples