Improve validation of sub range repair

also prevent "-pr" repair not to work with "-dc/-hosts/-local".
patch by yukim; reviewed by krummas for CASSANDRA-7317
Merge branch 'cassandra-2.0' into cassandra-2.1

Conflicts:
	src/java/org/apache/cassandra/service/StorageService.java
	src/java/org/apache/cassandra/tools/NodeCmd.java