removed -o & -ms-box-sizing

Never needed:
http://caniuse.com/css3-boxsizing
http://css-tricks.com/almanac/properties/b/box-sizing/
http://www.paulirish.com/2012/box-sizing-border-box-ftw/
Firefox will drop prefix soon: https://developer.mozilla.org/en-US/docs/Web/CSS/box-sizing, https://bugzilla.mozilla.org/show_bug.cgi?id=243412