verbosity for cb_sanity.sh script.

Change-Id: I195e797547564050ceac7c8e9b14091ab373fbd9
Reviewed-on: http://review.couchbase.org/43541
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>