Don't throw an exception when trying to stop a non-existent container
Set the status to stopped by ctrl-c

This covers scenarios where the container didn't start properly and
would otherwise result in the appearance of an endlessly running
scraper.

I think this fixes #377.
Add the ability to stop queued scraper too
Don't set start time if scraper didn't actually start
Merge pull request #426 from openaustralia/stop

Make stopping a scraper more reliable