MB-8909 Disallow spaces and control characters in bucket passwords.

Change-Id: Ie95a8e02c8955a0c385f201a9b797648a071d5c6
Reviewed-on: http://review.couchbase.org/28524
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>