[Fix id to _id](https://github.com/wekan/wekan/commit/2cedbcb9b334cd497874736bbb740a1d5c5acb6c#r34310594).

Thanks to justinr1234 and xet7 !

Related #802

models/org.js

@@ -5,7 +5,7 @@ Org = new Mongo.Collection('org');
  */
 Org.attachSchema(
   new SimpleSchema({
-    id: {
+    _id: {
       /**
        * the organization id
        */

models/orgUser.js

@@ -5,7 +5,7 @@ OrgUser = new Mongo.Collection('orgUser');
  */
 OrgUser.attachSchema(
   new SimpleSchema({
-    id: {
+    _id: {
       /**
        * the organization user's id
        */