Add i3status Portfile

[jenstroeger (Jens Troeger)]

Following up on ticket ​65811, and in particular ​this comment: the i3wm window manager (​i3 port) uses ​i3status by default to render data into its toolbar (managed by the i3bar tool). That i3status currently has no port.

I’m actually tempted to add i3status to the i3wm port because of their close dependency, instead of adding a new port. That would make testing and installing easier—running i3wm would work out of the box without needing another port.

Thought?