Make the fact work gracefully on systems that don't have FreeRADIUS

installed

lib/facter/freeradius_version.rb

 # Grab the FreeRADIUS version from the output of radiusd -v
-Facter.add(:freeradius_version) do
-  setcode do
-    Facter::Core::Execution.exec('radiusd -v').split(/\n/)[0].match(/FreeRADIUS Version (\d\.\d\.\d)/)[1]
+if %x{which radiusd 2>/dev/null | wc -l}.chomp.to_i > 0
+  Facter.add(:freeradius_version) do
+    setcode do
+      Facter::Core::Execution.exec('radiusd -v').split(/\n/)[0].match(/FreeRADIUS Version (\d\.\d\.\d)/)[1]
+    end
   end
 end