make alert_manager work with Docker

This pull request is to make alert_manager work with Docker. I have made a separate repository over in https://github.com/jamonation/alert_manager_docker.git, based on https://bugzilla.mozilla.org/show_bug.cgi?id=1034101

This repository is a git submodule inside the docker container so that it remains a separate python virtualenv for deployment purposes, while also working inside the Docker dev environment.

It will take a bit of testing and feedback to get the config.py just right, but I think this is enough to get things going.