Skip auth setup if AllowAllAuthenticator is used
Authorizer+authenticator configuration sanity check
Merge branch 'cassandra-1.2' into cassandra-2.0.0

Conflicts:
	src/java/org/apache/cassandra/config/DatabaseDescriptor.java
Merge branch 'cassandra-2.0.0' into cassandra-2.0
Merge branch 'cassandra-2.0' into trunk