Need to avoid issues caused by multiple node servers refreshing the token

[jimboca]

We had an issue where kubernetes shut down the node server to move it, but it took a long time for it to exit, then the new one started up but it's tokens were invalid by the time it tried to refresh them because the old one had done a refresh.

So need to create a wait_for_update function which:

• Checks that our current token is the latest token, in case someone already refreshed it
• Checks if someone else is updating the token, if not, then put info in the DB to say we are updating
  • If so waits for other to finish and passes back the new token
• Needs to time out based on the time the first one started the update

I think this catches everything, except a race condition that can occur at the start before we "lock" the db.

[jimboca]

Fixes are in 2.1.24, although as mentioned there is still a hole due to no DB locking.

[jimboca]

Fixed in 2.1.32 which does it's on db locking.