It is possible (likely) that a manage call is in progress when
`stop` is called. When that happens, _manage will continue to
run, and schedule another call - and the manager won't actually stop,
and will likely cause an error as other components have been torn down.
This fix adds a deferred that gets created when a manage call starts
and is fired when its done. At this points its safe to start the
stopping process. Also add a check to not schedule another manage
call if we're stopped
This fixes https://app.asana.com/0/142330900434470/239832897034382
cb2bb6ee6b