Service Broker provide tags as the result of a provision

Mike Youngstrom <youngm@...>

Looking at the service broker API it doesn't appear as though it is
possible for a service broker to provide tags as part of the provisioning
of a service instance.

I think it would be nice for a broker to automatically identify its own
service instances as a flavor of "mongodb" or "non-prod" service instance,
for example, without the user needing to do so manually.