[fix bug 1009511] Update sandstone Less mixins for transitions, transforms and animations

CSS transitions and keyframe animations can pretty safely drop all prefixes other than `-webkit-`. I've left in, `-ms-` prefix for CSS transforms, since it was partially supported in IE9 (2d only etc).

http://caniuse.com/#feat=css-transitions
http://caniuse.com/#feat=transforms2d
http://caniuse.com/#feat=transforms3d
http://caniuse.com/#feat=css-animation