More Complete Box-Sizing

Firefox is currently at version 29 according to http://caniuse.com/#search=box-sizing and still uses the -moz- prefix. It'd be nice to have a little support for that browser until a later time. It took me quiet some time figuring out why my grid rows didn't work. I'm not sure which mobile versions are supported by Foundation so I included the -webkit- prefix too.
Merge pull request #4848 from marclarr/patch-1

More Complete Box-Sizing