Code review comment for lp:~chipaca/ubuntu-push/client-session-redialer-mash

So, in this branch:
  * reworked redialer:
    * split Dialer into Dialer and Jitterer; only Jitterers are
      jittered. Also removed String from the Dialer interface.
    * moved the jitter default implementation to be the session's;
      moved the test
    * got rid of the AutoRedial/AutoRetry functions; always create an
      AutoRedialer (via NewAutoRedialer) and use it.
    * got rid of quitRedialing, because
    * gave AutoRedialers a Stop() method that would do the right
      thing.
  * session:
    * added AutoRedial, that sets up and launches an AutoRedialer on
      itself.
    * Close() now stops the AutoRedialer
  * client & session:
    * connectSession is now session.AutoRedial; got rid of the extra
      channel needed to be able to stop it. Renamed the channel used
      to communicate with the autoredialer for clarity.
    * disconnectSession is now session.Close()