Support object definition removal in awa-server-define

[thetoster]

It would be nice to have some configuration switch (or preferably script awa-server-undefine) which allow user to remove objects/resources definitions created by call to awa-server-define.

[DavidAntliff]

LWM2M requires both client and server to agree on object definition at all times, so it would be unwise to consider this as part of dynamic operation. However when considered as a function of server configuration, this may be a useful feature to add.