Use `\x0B` instead of `\v` for IE < 9 compatibility

See http://mathiasbynens.be/notes/javascript-escapes:

> IE < 9 treats `\v` as `v` instead of a vertical tab (`\x0B`). If cross-browser
> compatibility is a concern, use `\x0B` instead of `\v`.
Merge pull request #92 from mathiasbynens/patch-1

Use `\x0B` instead of `\v` for IE < 9 compatibility