hood files: Move files from /www to /tmp and link there

With this patch, changing the hood file happens in
memory, so we do not have to write on flash "frequently".

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
Reviewed-by: Robert Langhammer <rlanghammer@web.de>
Reviewed-by: Fabian Bläse <fabian@blaese.de>
Tested-by: Fabian Bläse <fabian@blaese.de>
Reviewed-by: Tim Niemeyer <tim@tn-x.org>