Fix: Fixed invalid path to country flags.

lib/vial/app.py

@@ -541,7 +541,7 @@ class Vial(flask.Flask):  # pylint: disable=locally-disabled,too-many-instance-a
                 return flask.Markup(
                     '<img src="{}">'.format(
                         flask.url_for(
-                            'design.static',
+                            'static',
                             filename = 'images/country-flags/flags-iso/shiny/16/{}.png'.format(
                                 country.upper()
                             )