Add widths for panel variants for each applicable breakpoint
Add widths for panel variants for each applicable breakpoint

zkoehne/Office-UI-Fabric,zkoehne/Office-UI-Fabric,waldekmastykarz/Office-UI-Fabric,OfficeDev/Office-UI-Fabric,waldekmastykarz/Office-UI-Fabric,OfficeDev/Office-UI-Fabric