Add a simple DBus service for setting a status

[festeh]

Hi!

I'm missing custom_dbus from another project and I'd like to add it here.

My motivation: sync a pomodoro timer app with status bar by providing custom hooks on timer events. In this case bar does not need to constantly poll for some resource, which I think is nice.

Would you be interested in this feature?

[kotontrion]

You can already achieve the same result using ags -r, which is way more powerful and versatile than this.

[festeh]

that's awesome, thanks!