Vuex (#8041)

* add vuex, cleanup client directory and create example components

* disale sample unit test

* disable import for non existing file

* correct regexp for unit tests, add simple test to avoid error, add babel-polyfill for Vuex

* add line wrongly removed, update regexp

website/client/components/siteHeader.vue

@@ -0,0 +1,20 @@
+<template lang="pug">
+h1 {{ title }}
+</template>
+
+<script>
+import { mapState } from 'vuex';
+
+export default {
+  computed: mapState([
+    'title',
+  ]),
+};
+</script>
+
+<!-- Add "scoped" attribute to limit CSS to this component only -->
+<style scoped>
+h1 {
+  color: #42b983;
+}
+</style>