Setup page on fresh install

[mrblacyk]

Make a setup page when there are no users nor settings in the database. So when a user (or in the future - a Dockerfile) does:

# migrate DB
./manage.py migrate

# start the app
./manage.py runserver 0:80

# or other more production deployment like apache2 with mod wsgi

..they are greeted with setup page. Probably this needs to be done as the last issue to contain the most settings.

[mrblacyk]

Very trivial page setup pushed in 95e885c