Fixes alignment of the header within a Contextual Menu when it's not multi-select.
Fixes alignment of the header within a Contextual Menu when it's not multi-select.

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