* On squeeze, use release fact instead of hardcoded release name
* On wheezy, special-case because codename selector is not available
* On jessie and up, start pulling in point-release updates. The
codename selector ensures that we won't be upgrading to a new
release automatically.
* Removes dependency on lsb-release and/or Facter >1.7
(values are based on $::lsbdistcodename, when available)
* Simplifies maintenance: only lib/facter/util/* require updates as new
releases are made
Caveats:
* apt::codename is removed; to override debian_* facts, set the
FACTER_debian_codename environment variable for puppet
* If tracking unstable, make sure lsb-release is installed, as other
methods can't tell between testing and unstable
This functionality was lost because we stopped using a source file for
the 50unattended-upgrades file that would previously let one override
the configuration per release or per host.
