Improve TemplateWidget JavaScript

Move widget initialization from form to field.

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

mayan/apps/templating/static/templating/js/template_widget.js

@@ -1,10 +1,10 @@
 'use strict';
 
 jQuery(document).ready(function() {
-    var fieldNameID = '#id_template_model_property';
+    var fieldNameID = '[data-template-fields="model_property"]';
     $(fieldNameID).change(function(event) {
         var $idModelProperty = $(this);
-        var $idTemplate = $('#id_template_template');
+        var $idTemplate = $('[data-template-fields="template"]');
         var templateCursorPosition = $idTemplate.prop('selectionStart');
         var templateValue = $idTemplate.val();
         var modelVariable = $idTemplate.data('model-variable');