add pip packaging process

Start building wahlfang as a pip package.

This has major implications though, especially for how settings are handled in a production deployment.

This MR implements changes such that we assume a settings file /etc/wahlfang/settings.py which imports and overwrites the base settings and is then loaded in the manage.py command and the wsgi and asgi application.

make package builds the python package

TODO:

• Think about the future - how do we handle a React app in the repo. Plug into the build process, create the minified bundled javascript and include that with the python package?