Clear error description should be provided by Magnum

In order to debug a failing bay creation, users need to know about interaction with heat, heat architecture and how to debug it. It would be much better if magnum could propagate some of the error description into the bay-show status.

For example if you get a case of stack failing because of:

| master_wait_condition | | OS::Heat::WaitCondition | CREATE_FAILED |

Magnum could create a text description in the stack status field saying something like "Waiting for XYZ connection to master instance failed" (I'm guessing, I have to read the heat template to figure out what it is at the moment)

Magnum doesn't have to do a full analysis / diagnosis, but even grabbing the first failing resource and describing it in simple summary would be very helpful.

The fact that heat descriptions exist on the server side makes this even more useful and current situation more difficult.