Makefile improvements

- Icons should be set to `-a icons=font`.
- Embedding the icons in the git repository is no more required.
- The Stylesheet is now embedded into the html files, so need to copy the
  stylesheets dir to the html directory.

Signed-off-by: Gael Chamoulaud <gchamoul@redhat.com>
Merge pull request #10 from strider/FixIcons

Makefile improvements