Point node.js "main" file to the built ./dist/vis.min.js` (see #1180)

package.json

@@ -21,7 +21,7 @@
     "network",
     "browser"
   ],
-  "main": "./index",
+  "main": "./dist/vis.min.js",
   "scripts": {
     "test": "mocha",
     "build": "gulp",

test/timeline_groups.html

@@ -221,7 +221,7 @@
     var logs = document.getElementById('logs');
     logs.innerHTML = msg + '<br>' + logs.innerHTML;
   }
-
+alert(1)
 </script>
 <div id="logs"></div>
 </body>