Device handlers should force reconfiguration whenever the device key does not match

[Alan Noble]

Currently, if the user changes the device key in the UI, it results in an error being returned to the device. Instead, response code (rc) 1 should be returned to force the device to reconfigure.

At present, only the config handler does this.

[Alan Noble]

Implemented in https://bitbucket.org/ausocean/vidgrind/commits/a45fa5edbc3cd87cc30bc5b574a2716bcb1cd49f