Major update to the pc-updatemanager utility.

Change how we perform updates to new "major" releases of Free/PC-BSD

Now, instead of relying on the always failing pkgng upgrade system, use
the pc-updatemanager to build lists of the old system pbis/pkgs/metapkgs
, install the new world / kernel and then re-install the PBIs / metapkgs.

As a bonus, we will now keep these lists, and generate a summary file which
can be used post-install to diagnose any potential problems during the upgrade.

I still need to finish some additional parsing to grab any user-installed pkgng
apps.