Clean up the CSS

We shouldn't force styling on application authors. And we should make it easy for them to style their applications however they please.

This isn't done yet. Here are a few other thoughts:
- [ ] Preface all CSS rules in index.css with `vwf-` to avoid potential name conflicts.
- [ ] Review the editor, overlays, and browser requirements warning to see if they need special styles since I took out a few global styles.
- [ ] Seek and destroy any further inline styles.
- [ ] Clean out the support/client/lib/images directory. Certainly some old stuff in there.