@btnBackgroundHighlight variable isn't used for background color of hovered and active button states

Created by: seanCodes

The @btnBackgroundHighlight variable isn't used for the background color of hover and active states for the default (gray) buttons. Changing the @btnBackgroundHighlight var in variables.less doesn't change the button background color, so the light gray background can be seen in the hovered and active states like so: http://jsfiddle.net/a2ZCP/3/