Fix apt_has_updates fact not parsing apt-check output correctly

The /usr/lib/update-notifier/apt-check script returns its output
to STDERR but a recent change to the script redirects STDERR to
/dev/null.  This will cause the array to always be empty.

Combined with that problem, while we were checking for the result
being nil, we never checked for an invalid array.  As a result,
the apt_has_updates was always true and the apt_updates and
apt_security_updates facts were trying to read from an empty array
and failing.

lib/facter/apt_updates.rb

@@ -2,18 +2,18 @@
 Facter.add("apt_has_updates") do
   confine :osfamily => 'Debian'
   if File.executable?("/usr/lib/update-notifier/apt-check")
-    apt_package_updates = Facter::Util::Resolution.exec('/usr/lib/update-notifier/apt-check 2>/dev/null').split(';')
+    apt_package_updates = Facter::Util::Resolution.exec('/usr/lib/update-notifier/apt-check 2>&1').split(';')
   end
 
   setcode do
-    apt_package_updates != ['0', '0'] unless apt_package_updates.nil?
+    apt_package_updates != ['0', '0'] unless apt_package_updates.nil? or apt_package_updates.length != 2
   end
 end
 
 Facter.add("apt_package_updates") do
   confine :apt_has_updates => true
   setcode do
-    packages = Facter::Util::Resolution.exec('/usr/lib/update-notifier/apt-check -p 2>/dev/null').split("\n")
+    packages = Facter::Util::Resolution.exec('/usr/lib/update-notifier/apt-check -p 2>&1').split("\n")
     if Facter.version < '2.0.0'
       packages.join(',')
     else