progress bar loading ajax
xhr: function() {
var xhr = new window.XMLHttpRequest();
xhr.upload.addEventListener("progress", function(evt) {
if (evt.lengthComputable) {
var percentComplete = Math.ceil((evt.loaded / evt.total) * 100);
$(".uk-progress").width(percentComplete + '%');
$(".uk-progress").html(percentComplete+'%');
}
}, false);
return xhr;
},