[Galene] Bearer tokens in the administrative API

[Juliusz Chroboczek <jch@irif.fr>]

I've just pushed code to authentify using bearer tokens in the
administrative API.  This touches a lot of the auth code, albeit in minor
ways; I've tried to be careful, and hopefully didn't introduce any
security flaws.

Assuming you've got galenectl configured, crate a global admin token:

  galenectl -insecure create-token -group "" -include-subgroups -permissions admin

Now edit your galenectl.json file: remove the "admin-password" field, and
replace it with an "admin-token" field that contains the newly generated
token.

While in principle the code supports cryptographic tokens (JWTs), in
practice it won't work with them, since there are no global keys yet.  I'm
not quite sure where to store global keys: in the config file?  In
a separate JWK file?

In the first place: what are the use cases for global stateless tokens?

-- Juliusz