add polyfill for IE (#8)

1. use if comment to include scirpt only for IE
2. use html-webpack-plugin to inject file hash

source/app/index.jade

@@ -1,5 +1,5 @@
 doctype html
-//- variable `app` here is used by gulp
+//- variable `app` here is used by build script
 html(lang="en", ng-app= app, ng-strict-di)
     head
         //- This helps the ng-show/ng-hide animations start at the right place.
@@ -11,6 +11,10 @@ html(lang="en", ng-app= app, ng-strict-di)
         meta(http-equiv="X-UA-Compatible", content="IE=edge, chrome=1")
         meta(name="viewport", content="width=device-width, initial-scale=1, maximum-scale=1, minimum-scale=1, user-scalable=no")
         base(href="/")
+        // babel polyfill for IE
+        <!--[if IE]>
+        <script src="ie-polyfill.{%=o.webpack.hash%}.js"></script>
+        <![endif]-->
 
     body(ng-class="_class + '-page'")
         .wrapper(ui-view)

webpack.config.js

@@ -68,7 +68,8 @@ module.exports = {
             'angular-mocks',
             'angular-loading-bar',
             'oclazyload'
-        ]
+        ],
+        'ie-polyfill': 'babel-core/polyfill.js'
     },
     output: {
         path: base + 'build',