Update Escodegen and Esmangle dependencies

Ref. #2.
Test if `\x0B` is used instead of `\v`

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`.

Ref. #2.
Tag the v0.2.1 release