convert timesheets to UTC with support for user timezone (#372)

assets/js/kimai.js

@@ -5,10 +5,17 @@
  * file that was distributed with this source code.
  */
 
+/** global: jQuery */
+/** global: moment */
+
 if (typeof jQuery === 'undefined') {
     throw new Error('Kimai requires jQuery');
 }
 
+if (typeof moment === 'undefined') {
+    throw new Error('Kimai requires moment.js');
+}
+
 /* kimai
  *
  * @type Object