Fix concurrent tests.

Running jest runs the two test suites in parallel. If both try to run a server on port 3000, only one of them will succeed and supply files for both, however when that suite finishes first, it will take down the server and leave the other one hanging. Fix this by running the servers on different ports.

integration/widget.test.js

@@ -3,14 +3,14 @@ const express    = require('express');
 
 const puppeteer = require('puppeteer')
 
-const rootUrl = "http://localhost:3000/";
+const rootUrl = "http://localhost:3001/";
 
 jest.setTimeout(500000);
 
 const server = new Promise( resolve => {
     let app = require( '../src/server' )({ directory: path.join( __dirname, '..' ) });
     let server;
-    server = app.listen( 3000, () => resolve(server) );
+    server = app.listen( 3001, () => resolve(server) );
 }).catch( e => console.log(e) );
 
 const browser = puppeteer.launch({ headless: false });