added image and stls for printed stepper

printed-stepper/bottom.stl

printed-stepper/hex.stl

printed-stepper/printed-stepper.jpg

printed-stepper/rotor-layer-A.stl

printed-stepper/rotor-layer-B.stl

printed-stepper/stator.stl

printed-stepper/stator2.stl

printed-stepper/stator3.stl

printed-stepper/top.stl