Introduces a special server mode for when the build fails.

Instead of just exiting on a failed load this code puts the server in a wait mode. The only way to get out of this mode is to either exit or send a ``reboot`` command. For all other commands the server will just continue in the wait mode.
Comments are welcome as there might be something I have missed in terms of error handling etc.
didn't we send this already or would this be the first time? we don't need to send it more than once per load failure surely