set us up on openhatch

[Will Kahn-Greene]

I haven't checked out the state of things, so I don't know where
they're at.

MediaGoblin should have a solid presence on OpenHatch
(`http://openhatch.org/ <http://openhatch.org/>`_). This includes:


-  asking and answering the big questions on the project page
-  setting openhatch up to track our bitesized bugs (see issue
   `#382 </issues/382>`_)
-  getting a workflow set up so that when someone is interested in
   helping out, someone is notified and someone reaches out