Merge pull request #3 from dev-sec/chris-rock/fix-unsupported-os

return empty array, if the operating is not supported

Author: chris-rock

libraries/windows_updates.rb

@@ -106,10 +106,12 @@ def select_update_mgmt
   end
 
   def fetchUpdates
+    return [] if @update_mgmt.nil?
     @update_mgmt.fetchUpdates
   end
 
   def hotfixes
+    return [] if @update_mgmt.nil?
     @update_mgmt.hotfixes
   end
 end