Add basic notification support.

src/components/notifications/notifications.js

@@ -0,0 +1,16 @@
+import { sortBy, take } from 'lodash'
+
+const Notifications = {
+  data () {
+    return {
+      visibleNotificationCount: 20
+    }
+  },
+  computed: {
+    visibleNotifications () {
+      return take(sortBy(this.$store.state.statuses.notifications, ({action}) => -action.id), this.visibleNotificationCount)
+    }
+  }
+}
+
+export default Notifications