bug 895771 - fix jenkins tests

Subtree merging socorro-crashstats went smoothly for the repository, but it messed up all our build infrastructure. An earlier PR attempted to fix this and after 24 hours I was spinning yak wool into yarn and Jenkins remained broken.

The ambition is to:
- [x] define webapp-django commands
- [x] have leeroy run both socorro and socorro-crashstats tests
- [x] deposit webapp-django in the output tar

On Monday operations will modify the deploy process for the webapp to work with the new output format.