Driver binaries updated to 0.12.1-rc

Driver binaries updated to latest version and added additional driver info.

This solves some nasty bugs we ran into (eg. [Table do not break well across pages][1]) and [bunch of other things][2]. Current driver are VERY old (from [April/May 2010][3]), but I don't know is there some good reason for that.

  [1]: https://code.google.com/p/wkhtmltopdf/issues/detail?id=566
  [2]: https://github.com/wkhtmltopdf/wkhtmltopdf/blob/c22928d/CHANGELOG.md
  [3]: http://code.google.com/p/wkhtmltopdf/downloads/list?can=1

/cc #16