Vedeu related changes.

- Remove view tests; Vedeu has changed dramatically.
- Bump vedeu dependency to 0.2.4.
- Use #width instead of #viewport_width.
- Configure application with sensible defaults.
- Vedeu no longer supports `cursor` like this.
- Use Vedeu's new 'keys' API.
- Improve views;

  In deprecating the subclassing of Vedeu::View and with the addition of
  Vedeu.render, rendering views has been simplified. Also, the controller has
  been refactored, and finally the Vedeu dependency version has been bumped
  to 0.2.1.