Implements autoActive() for listrotator widget

Allows to check whether the "auto" button is currently active on the widget.
Also removed the "auto" option in this change since the option has no effect on the widget even
though it was documented and has a default value. "auto" is just always active on initialization.

Change-Id: I57a6ad92c010a1e577b2418a6fabf63652ad6def
Merge "Implements autoActive() for listrotator widget"