Make the index page behind auth

This patch makes the index page ask for login/password in order
to see the stats.

aprsd/flask.py

@@ -41,6 +41,7 @@ class APRSDFlask(flask_classful.FlaskView):
 
         users = self.users
 
+    @auth.login_required
     def index(self):
         return flask.render_template("index.html", message=self.stats())