Increase the speed of xletsettings

This change update the settings(xlet) using DBus signals. Will stopped the file monitor(for the .json file), if settings can connect to DBus to realize the update. I know that will be better the use of GDBus instead of DBus on cinnamonDBus.js, but this could changed afterwards. I don't know if will be good also send a signal to update all settings or if will be better using the file monitor for update all settings, when occurs a change in .json, but just now Cinnamon has a duplicate mechanism for update the settings. only partially from the value of the attributes, do not a complete update and this could be good for devs. So the file monitor continues active if DBus it's not active. This is the current way.