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.
Thought it would be a good idea to always reply with a reminder in case they continue to send non-reboot commands?