[registry] backout 120c7ea6e1fa: errors should not pass silently Catching ImportError silently while loading files has too many side effects. (e.g. if system hooks / entities can't be registered).

bgcolor = '#000000'
stylesheets = ['%s/cubicweb.css' % datadir_url]
logo = '%s/logo.png' % datadir_url
lazy = lazystr('%(bgcolor)s')