tests: load 3rd-party libs from the local node_modules folder.

This reduces duplication and the chances to forget to update something.

Author: XhmikosR

js/tests/index.html

@@ -22,11 +22,11 @@
     <script src="../../assets/js/vendor/popper.min.js"></script>
 
     <!-- QUnit -->
-    <link rel="stylesheet" href="https://code.jquery.com/qunit/qunit-2.4.1.css" media="screen">
-    <script src="https://code.jquery.com/qunit/qunit-2.4.1.js"></script>
+    <link rel="stylesheet" href="../../node_modules/qunitjs/qunit/qunit.css" media="screen">
+    <script src="../../node_modules/qunitjs/qunit/qunit.js"></script>
 
     <!-- Sinon -->
-    <script src="https://cdnjs.cloudflare.com/ajax/libs/sinon.js/4.4.6/sinon-no-sourcemaps.min.js"></script>
+    <script src="../../node_modules/sinon/pkg/sinon-no-sourcemaps.js"></script>
 
     <script>
       // Disable jQuery event aliases to ensure we don't accidentally use any of them