I don't think we're gonna like plymouth over rescue image
anytime soon, especially when it hides the moment when shell
pops up somewhere under it without startup-rescue caring to
remove the splash.

So let's put that $(INSTALL2_BRANDING) into proper stage2
flavours only and avoid choking on missing plymouth as well.

It appeared that plymouthd.conf wasn't set up properly
thus "service plymouth stop" didn't result in anything
meaningful; thanks boyarsh@ for his help figuring this
out again.

An initial draft of it was done half a year ago but several tricky
thingies had kept the code from showing up as it was rather brittle
and incomplete.

This implementation involves quite a few changes all over the place
but finally works good enough for live and installer images.

Please pay attention to the versions of these packages:
- installer-feature-setup-plymouth (0.3.2-alt1+)
- branding-altlinux-sisyphus (20110706-alt2+ if used)
- plymouth (0.8.3-alt20.git20110406+)

See also:
- http://www.altlinux.org/Branding
- http://www.altlinux.org/Plymouth