Add Desktop notifications (#252)

* Add notifications

* Abide push actions

* Handle browsers not having notification support

* Ask for notification permission after loading

* Make usePermission work without live permission support

* Focus message when clicking the notification

* make const all caps

* Fix usePermission error in Safari

* Fix live permissions

* Remove userActivity and use document.visibilityState instead

* Change setting label to "desktop notifications"

* Check for notification permissions in the settings.js

src/client/action/settings.js

@@ -30,3 +30,9 @@ export function toggleNickAvatarEvents() {
     type: cons.actions.settings.TOGGLE_NICKAVATAR_EVENT,
   });
 }
+
+export function toggleNotifications() {
+  appDispatcher.dispatch({
+    type: cons.actions.settings.TOGGLE_NOTIFICATIONS,
+  });
+}