* Major update to how we do Major Updates

* First, we are dropping the fragile freebsd-update system for doing
  major updates, I.E 10.0 -> 10.1

* Instead switch to grabbing the PC-BSD ISO file, for the major release
  - Do full verification of this ISO file, contents, etc
  - Extract the base/kernel/games/doc/lib32*.txz files
  - Added support for our custom version of "etcmerge" to handle updates
    to /etc
  - System Packages will be installed from the DVD / ISO, preventing issues
    with connectivity problems, and pkgng "hiccups" getting files from the
    net.
  - PBIs will be fetched from internet, but if they fail, will not prevent
    user from getting back to a desktop where they can re-install via AppCafe

* While here, added support for automatic creation of a Boot-Environment before
  the update is started