Server creation logic

[DaneEveritt]

Due to the potential for the server creation on the daemon to take awhile (i.e. new image or image update) we should send a HTTP/202 response as soon as we process the request, and then notify the panel of a successful install using the normal install endpoint, and also include an endpoint to hit if there was an error.

If that error endpoint is hit, the panel immediately deletes the server and associated systems with it.

This system should also allow configuration so that the panel can hit additional endpoints on other services on success or failure for ease of integration with billing systems.

[DaneEveritt]

Implemented in be47565