Refactor Slider.less, ProgressBar.less and fix two minor position issues...

.... Enyo-DCO-1.1-Signed-off-by: Brooke Peterson <brooke.peterson@lge.com>
Is this something that every app developer will have to do to achieve the same effect? If so, this should be included in the control's definition, and not in the sample/app. Having to put ` position: relative; top: -5px` on every input decorator would get tedious quickly.