Break policycoreutils out into separate packages for the various utilities.

The driver beind this is to allow images to be built with the minimal
tools necessary to load a policy.  Breaking all of the stuff that's
dependent on python out from the core utils allows us to make much
smaller images.
Remove unnecessary RDEPENDS_${BPN}.

Now that the policycoreutuils package is empty no need for RDEPENDS.
Doing this in the commit that broke up the policycoreutuils package
made the diff hard to read. Figured it best to break it out for
readability.
Remove runtime dependency on policycoreutils from the reference policy.

The only thing refpol needs to depend on at runtime are the things
necessary to load the policy.  If sysvinit is patched to load the
policy (which it is) then we only need the config.
Add packagegroup and image recipe for minimal SELinux image.

This is intended to demonstrate the minimal set packages necessary
to boot and load a system with SELinux enabled. Specifically we
don't need any of the packages that depend on python.
Add packagegroup for policycoreutils packages.

The policycoreutils package previously included most everything in
the base package. This packagegroup is intended to fill the role
of the old policycoreutils package and pull in all packages from the
policycoreutils recipe.