Don't remove debian subdirectory if it exists on git cleanup.

This doesn't harm if you don't build a Debian package as `git cleanup` will work
just fine if the `debian` directory does not exist. Without this patch the
`distclean` rule will also remove the `debian` directory which make it
impossible to correctly build a debian package.
Replaced jquery-ui.min.js with uniminified versions.

Concatenated jquery.effects.core.js jquery.effects.slide.js from jquery 1.8.18
to one file and changed the original reference in layout.html to the new
filename.
Added debian dir
Added python3 packaging.
Added python3-kivy.install