Closes #52. Add Power module

This module displaysw which source is providing power (AC or battery)
and for the battery displays the current charge capacity, how long it
will last, and the battery state.

cmdrunner/widget.go

@@ -21,7 +21,6 @@ type Widget struct {
 }
 
 func NewWidget() *Widget {
-
 	widget := Widget{
 		TextWidget: wtf.NewTextWidget(" 🏃 Runner ", "cmdrunner", false),