Create a deployable python egg 

I've made a bunch of changes, which may or not may fit with the way you are using the containerizer.

1) We create an installable python egg using the `Makefile`
2) The `environment.sh` file is moved to `/etc/default/containerizer`
3) The `setup` script, `requirements.pip` and virtual environment are located in `/opt/containerizer`
4) The `setup` script sets up the virtualenv in `/opt/containerizer/env`

This means we can install the egg, run `/opt/containerizer/bin/setup` once.
If you wouldn't mind rebasing over the top of master, and i'll give this change a go and see :thumbsup: