Add Failure:: symbol to fail_with

Author: espreto

modules/exploits/unix/webapp/wp_slideshowgallery_upload.rb

@@ -103,10 +103,10 @@ def exploit
       if res.code == 200
         register_files_for_cleanup(filename)
       else
-        fail_with("#{peer} - Unable to deploy payload, server returned #{res.code}")
+        fail_with(Failure::Unknown, "#{peer} - Unable to deploy payload, server returned #{res.code}")
       end
     else
-      fail_with('ERROR')
+      fail_with(Failure::Unknown, 'Server did not respond in an expected way')
     end
 
     print_status("#{peer} - Calling uploaded file #{filename}")