single notification display and nicer list

src/common/pages/MainPage/MainPage.js

src/common/pages/Notification/NotificationPage.js

src/components/devices/AddDevice.js

src/components/preferences/AddPreference.js

src/notifications/actions/GetNotifications.js

...cations/components/NotificationsList/NotificationsList.js

...tions/components/NotificationsList/NotificationsList.scss

...otifications/pages/NotificationsPage/NotificationsPage.js

src/notifications/reducers/NotificationsList.js

src/registerServiceWorker.js

src/utils/notification-type-icon.js