Replace ?mobilecomponents?.IconButton with PlasmaComponents.ToolButton

I estimated the button size. they might seem visually smaller but the surface you can hit to trigger should be about the same.

This is my fist patch to Plasma Active.
I did not subscribe to the plasma list when I first tried to submit this to reviewboard. 
So sorry for the spam if this comes through twice.

build + installed with kdesrc-build. viewed with plasmoidviewer

could not test the video playback as that didn't work before either.