Replaced moment.js with Javascript date.

Thanks to xet7 !

models/wekanCreator.js

@@ -1,9 +1,28 @@
 import { ReactiveCache } from '/imports/reactiveCache';
-import moment from 'moment/min/moment-with-locales';
+import { 
+  formatDateTime, 
+  formatDate, 
+  formatTime, 
+  getISOWeek, 
+  isValidDate, 
+  isBefore, 
+  isAfter, 
+  isSame, 
+  add, 
+  subtract, 
+  startOf, 
+  endOf, 
+  format, 
+  parseDate, 
+  now, 
+  createDate, 
+  fromNow, 
+  calendar 
+} from '/imports/lib/dateUtils';
 
 const DateString = Match.Where(function(dateAsString) {
   check(dateAsString, String);
-  return moment(dateAsString, moment.ISO_8601).isValid();
+  return isValidDate(new Date(dateAsString));
 });
 
 export class WekanCreator {