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/). This includes:

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