0.3.1

Fixed

• A session that joins a running workspace no longer leaves it up for nobody.
  Joining used to decide the close-down on its own: a joined session always left the
  workspace running, so the next openreynolds found it still up, printed "joining
  the workspace already running", and left it up again -- relaunching the CLI kept an
  idle container alive (and billing) indefinitely, with no session on the web to
  explain it. A joined session now asks the same questions as one that started the
  workspace -- running job rows, and the probe for another session's processes -- and
  stops it when nobody is working on it. A sibling session that is live but idle at
  that moment starts a fresh container on its next call; the volume is untouched.
  Studies with no directory of their own still leave a joined workspace up.