Use unicode symbols for sort arrows
Use unicode symbols for sort arrows

Change-Id: I0ecc983287970687faa5438e515ff25b9395824f

shahrzadmn/vaadin-grid,shahrzadmn/vaadin-grid,jforge/components,manolo/components,jforge/components,jforge/components,shahrzadmn/vaadin-grid,manolo/components,manolo/components,shahrzadmn/vaadin-grid