add tagline to default theme

This is probably the first thing everyone will remove, so maybe we
should move it into a hook.

Fixes #161
fix: daemon serves data with wrong charset

The Mojolicious reply->asset helper does not set the right content type
automatically for you. But the reply->static helper does! So, we load
the file and then throw it away (which is fine because no actual content
got loaded yet... I hope).

Fixes #168