Writing of config entries entries

When writing an entry, a 5 second timer is started until the config is
synched, this also compresses multiple config changes in quick
succession into one sync event.

This seems to work quite well already for clearing the browser's history
and enabling / disabling adblock. The webbrowser doesn't correctly
reload history while running, it reloads but reads the old config
apparently, so the history isn't cleared until restart.