Prevent tap highlight on Mobile Safari

When I touch a input tag on webkit based mobile browsers (Safari and Chrome), it appears a gray box overlay on input tag. It's not very good. I checked Bootstrap 3 and it disabled this behavior. So I google for the solution and add  this pull request.

You can also see this:
http://stackoverflow.com/questions/3463527/when-you-touch-an-html-element-in-safari-on-the-ipad-it-turns-gray-what-is-the