The correct scope to ask for is not devstorage.editor, but
cloud-platform. This will, rather than returning a signed JWT from
Google that looks like it works but doesn't, return a JSON object
containing an access token and expiration time.
Moves =, closer to call sites so it's clearer what's coming from where.
Also uses +ot, allowing a less horrifying +sign-jwt. This also seems to
not jump back and forth between tapes and cords as much, for what that's
worth.
