[WIP] adding test for admin dashboard app

This tests fails because the login form does not become visible.
There are no JS errors and the CSS is fine. My guess is that the
HTML generated by the dashboard app is invalid. If I comment out
the current `<body>` tag with its `<script>` tags and replace it with
the static HTML from Chrome's inspector, it works all fine. Well
possible that Chrome auto-fixed the HTML.

Next step would be to look trough the templates of the admin dashboard
app and look for tags that don't get closed.