Cleanup static files

"terminate with extreme prejudice"

- [] move app-specific static files to `appfolder/static/appname`
- [] separate bootstrap files into `css/` `fonts/` and `js/`
- [] delete `jquery/`?
- [] update `absent_trainee_roster` to use `django-select2` and consolidate select2 files
- [] use minified js/css and `.map` files for debugging