Fix missing progress bar in files drop view

The uploader is expecting the progress bar element to be in the DOM when
created. This fix makes sure to append the PublicUploadView's element to
the DOM before rendering it.

apps/files_sharing/js/PublicUploadView.js

@@ -152,9 +152,10 @@
 		var view = new OCA.Sharing.PublicUploadView({
 			shareToken: $('#sharingToken').val()
 		});
+		$('#preview .uploadForm').append(view.$el);
+
 		view.render();
 
-		$('#preview .uploadForm').append(view.$el);
 		$('#uploadprogresswrapper .stop').on('click', function () {
 			view.onUploadCancel();
 		});