api: fix the sort field when inserting a swimlane or a list

This has the side effect of always inserting the element at the end.

models/lists.js

@@ -314,9 +314,11 @@ if (Meteor.isServer) {
     try {
       Authentication.checkUserId( req.userId);
       const paramBoardId = req.params.boardId;
+      const board = Boards.findOne(paramBoardId);
       const id = Lists.insert({
         title: req.body.title,
         boardId: paramBoardId,
+        sort: board.lists().count(),
       });
       JsonRoutes.sendResult(res, {
         code: 200,

models/swimlanes.js

@@ -256,9 +256,11 @@ if (Meteor.isServer) {
     try {
       Authentication.checkUserId( req.userId);
       const paramBoardId = req.params.boardId;
+      const board = Boards.findOne(paramBoardId);
       const id = Swimlanes.insert({
         title: req.body.title,
         boardId: paramBoardId,
+        sort: board.swimlanes().count(),
       });
       JsonRoutes.sendResult(res, {
         code: 200,