Explicit mime type for .ttf font files

Fix for https://github.com/gae-init/gae-init/issues/53 *"Could not guess mimetype warnings for .ttf files"* including comment in the `app.yaml` that order is important: the `url: /p/font/(.*\.ttf)` handler must precede the `url: /p/` handler so that Google App Engine can provide gzip encoding/compression on these .ttf font files.

Note that changing order doesn't break anything, it just doesn't get you the compression and bandwidth/time benefits, therefore a "must" (and not a "shall").