Merge pull request #4707 from owncloud/use_on_instead_of_deprecated_bind

use on to add event listener instead of deprecated jquery bind

core/js/oc-requesttoken.js

-$(document).bind('ajaxSend', function(elm, xhr, s) {
+$(document).on('ajaxSend',function(elm, xhr, s) {
 	xhr.setRequestHeader('requesttoken', oc_requesttoken);
 });
+