Don't announce schema version until we've loaded the changes locally

patch by slebresne; reviewed by iamaleksey for CASSANDRA-5904
Merge branch 'cassandra-1.2' into cassandra-2.0.0

Conflicts:
	CHANGES.txt
Merge branch 'cassandra-2.0.0' into cassandra-2.0
Merge branch 'cassandra-2.0' into trunk