Add synchronous mode for starting a deploy and monitoring the status of the deploy

[bmorton]

The asynchronous mode of deploys is good for many use-cases and makes things quite a bit simpler, but it leaves the person deploying a little unsure about what is going on. We should support both modes:

• Trigger deploy and return immediately
• Trigger deploy and stream as much information about the deploy back to the client

I'm not too sure which should be the default yet.

[bmorton]

Thinking about this more, I think keeping this as two different endpoints would be ideal. You could kick off the deploy and make a second request to follow the progress of that deploy. This would allow deployctl to support a "synchronous" mode by making both requests.