/submit and /status endpoints

Allows users to submit jobs for bulk queries. In this pull request we have the /submit endpoint for submitting jobs, the /status endpoint for getting the status of jobs (and the URL of the output when the job succeeds), and the actual job runner itself, which runs as part of fedmsg-hub.

Advanced queries are thrown out the window until we can come up with a way to do it that doesn't require inventing a new language, or until we invent a new language that isn't baked into the datagrepper system.

There is no auth yet. I want to get this merged in so we can make a beta release and push it to staging while I figure out auth.

Will close #18 and #19.