Don't use asset pipeline (doesn't work with our OBS packages)

 * The user running the application should have permissions to write in
   the 'public/stylesheets' directory of the host application.
 * application.css (good old CSS now) is copied there during application
   startup.
 * A version number is used to emulate some of the advantages of asset pipeline
   digesting. Should be manually updated when changing application.css. We can
   change to a better solution afterward.