Move notifications to the top

This avoids notifications getting covered by the player

ui/src/layout/Notification.js

@@ -0,0 +1,11 @@
+import React from 'react'
+import { Notification as RANotification } from 'react-admin'
+
+const Notification = (props) => (
+  <RANotification
+    {...props}
+    anchorOrigin={{ vertical: 'top', horizontal: 'center' }}
+  />
+)
+
+export default Notification