Refactor client-side access checks.

Go from a Vuex based to a mixin based approach.

lib/www/client/source/src/components/app-bar-extension-project.vue

@@ -1,7 +1,7 @@
 <template>
   <v-tabs :value="tab" show-arrows v-if="page != 'configuration'">
     <v-tab v-for="tab, index in tabs" :key="index" link :to="tabLink(tab.href)" v-text="tab.text"></v-tab>
-    <template v-if="adminaccess">
+    <template v-if="adminaccess()">
       <v-spacer></v-spacer>
       <v-tab :to="tabLink('configuration')" class="orange--text darken-3" title="Edit project settings"><v-icon small left color="orange darken-3">mdi-cog-outline</v-icon> Settings</v-tab>
     </template>
@@ -15,9 +15,15 @@
 
 <script>
 import { mapActions, mapGetters } from 'vuex';
+import AccessMixin from '@/mixins/access';
 
 export default {
   name: 'DougalAppBarExtensionProject',
+
+  mixins: [
+    AccessMixin
+  ],
+
   data() {
     return {
       tabs: [
@@ -44,7 +50,6 @@ export default {
       return this.tabs.findIndex(t => t.href == this.page);
     },
 
-    ...mapGetters(["adminaccess"])
   },
 
   methods: {