Added TickLabelSpec to test that tick labels are rendering correctly.
Added TickLabelSpec to test that tick labels are rendering correctly.

rgnevashev/bootstrap-slider,gormanb/bootstrap-slider,rbojha/bootstrap-slider,serbiant/bootstrap-slider,rgnevashev/bootstrap-slider,serbiant/bootstrap-slider,pelex/bootstrap-slider,rbojha/bootstrap-slider,sifex/bootstrap-slider,rbojha/bootstrap-slider,gormanb/bootstrap-slider,sifex/bootstrap-slider,pelex/bootstrap-slider