cqlsh: ignore .cassandra permission errors

patch by Mihai Suteu; reviewed by Mikhail Stepura for CASSANDRA-7266
Merge branch 'cassandra-1.2' into cassandra-2.0

Conflicts:
	CHANGES.txt
Merge branch 'cassandra-2.0' into cassandra-2.1
Merge branch 'cassandra-2.1' into trunk