stadion: move model Anlage to stadion app
meeting: add stadion to detail template
meeting: use class based views
add root index page
meeting: fix href in meeting's index.html
stadion: fix delete view
stadion: add delete button to detail view
stadion: add 'Add new Stadion...' button to index view
stadion: have heading always displayed
add bootstrap
stadion: have bootstrap loaded for index view