Create a rolling API token and auto retry on token rejection.

[breautek]

Currently a FuseContext API Server generates an API token when the server is created and then remains constant for the lifetime of the API server.

This imposes a security risk should the token be leaked by some other exploit on the application where that token will remain valid for as long as the activity remains active (not destroyed).

We can minimise this risk by making the API token short-lived, (30-60 seconds?).