Basic support for unit testing added yeoman#759

- Babel config now supports modules (imp/exp)
-  Added module support in the index.html
-  Added sample function in main.js for future unit testing
- Tests updated

app/templates/babelrc

@@ -1,5 +1,10 @@
 {
   "presets": [
-    "@babel/preset-env"
+    ["@babel/preset-env",       {
+      "sourceType": "unambiguous",
+      "targets": {
+        "esmodules": true
+      }
+    }]
   ]
-}
+}

app/templates/index.html

@@ -116,7 +116,11 @@ <h1>'Allo, 'Allo!</h1>
     <%_ } -%>
     <!-- endbuild -->
     <!-- build:js scripts/main.js -->
+    <%_ if (includeUnit) { -%>
+    <script type="module" src="scripts/main.js"></script>
+    <%_ } else { -%>
     <script src="scripts/main.js"></script>
+    <%_ } -%>
     <!-- endbuild -->
   </body>
 </html>

app/templates/main.js

@@ -1,4 +1,12 @@
-console.log('\'Allo \'Allo!');
+<%_ if (includeUnit) { -%>
+export function greeting() {
+    return '\'Allo \'Allo!';
+}
+
+console.log(greeting());
+<%_ } else { -%>
+    console.log('\'Allo \'Allo!');
+<%_ } -%>
 
 <%_ if (includeBootstrap) { -%>
 // Uncomment to enable Bootstrap tooltips