Endpoint for Posting a Mission File

[walterroach]

This is the only change I needed to make to Tauntaun to allow for sending missions to it from Liberation via the "takeoff" button.

This should not be merged as-is. However, if a similar endpoint can be defined that properly requires some authentication and sanitizes the input (and probably should broadcast the mission load event to connected clients), then I can adjust the simple client I built in Liberation to post a file according to that definition.