Remove $apt_unattended_upgrades

Unattended upgrades are not always necessary. Including the
apt::unattended_upgrades class through the main apt class is not
appropriate. It is better to make nodes include the
apt::unattended_upgrades class explicitly.

Remove the $apt_unattended_upgrades variable along with the include in
the 'apt' class.

Signed-off-by: Gabriel Filion <lelutin@gmail.com>

manifests/init.pp

@@ -48,14 +48,12 @@ class apt {
       include apt::preferences::absent
     }
     default: {
+      # When squeeze becomes the stable branch, transform this file's header
+      # into a preferences.d file
       include apt::preferences
     }
   }
 
-  if $apt_unattended_upgrades {
-    include apt::unattended_upgrades
-  }
-
   # watch apt.conf.d
   file { "/etc/apt/apt.conf.d": ensure => directory, checksum => mtime; }