Use MutationObserver to detect if a saveProgress event was received,
which will trigger an animation.
Before this, `helper.admin$('#response').is(':visible')` was true
after the page loaded and before clicking the Save button, so there
was a possibility that after clicking Save, but before sending the
socketio message to the server, the visibility is checked and returns
true, so the page gets reloaded before the changed settings have been
saved.
