The OLED display should indicate need for firmware upgrade

[mjstn]

Because our host code now can use the OLED display which it does for IP viewing and battery level we need more.

We should verify the firmware rev is not quite old and indicate firmware rev with 'UPGRADE' if it's really old.
So far we do battery and IP messages in the oled node. The oled node was written to support display updates through a topic and all that is in now so I suggest we start to do other messages from motor node using that topic.