Adding start/stop functionality in manage.py (#457).  source.py and jour...

...nalist.py create a pidfile (the path of which is defined in config/base.py) and this is referenced for shutdown.
A more robust solution would be to poll until those processes are no longer running, e.g.

```
def poll_servers():
    while True:
        # check if the servers are running using psutil
        if servers_running:
            time.sleep(0.1)
        else:
            return
```