MB-100: define allowed hosts in buildout config

Change-Id: Ifef088741e2250ddd3e4aa3b9e755dd4411bdb8e
Reviewed-on: http://review.couchbase.org/25187
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>
Tested-by: Pavel Paulau <pavel.paulau@gmail.com>