Removes removeAttr('checked') in favor of setting property to 'false'

https://api.jquery.com/removeprop/
https://jquery.com/upgrade-guide/3.0/#breaking-change-removeattr-no-long
er-sets-properties-to-false

Author: Kevin Morris

src/jquery.loadJSON.js

@@ -92,7 +92,7 @@
 					if (value.toString().toLowerCase() == element.value.toLowerCase()) {
 						$element.prop('checked', true);
 					} else {
-						$element.removeAttr('checked');
+						$element.prop('checked', false);
 					}
 					refreshMobileCheckBox($element);
 					break;
@@ -103,7 +103,7 @@
 					if ((value.constructor == Array && value.contains(elementValue)) || value == elementValue) {
 						$element.prop('checked', true);
 					} else {
-						$element.removeAttr('checked');
+						$element.prop('checked', false);
 					}
 					refreshMobileCheckBox($element);
 					break;