Server should remove list of instruments from resources when starting.

[RBerliner]

If an instrument fails and must be disconnected (like and electronic compass), on restarting the server, the last compass reading is still used and the server uses this value (instead of the GPS) to calculate heading.

In order to remove the failed instrument from the list of resources, it is necessary to do a clean start with with self.json, signalk-config.json, etc. deleted and build them anew.