Updated wkhtmltopdf to version 0.12.1

Updated wkhtmltopdf binaries to 0.12.1 to include bug fixes on that
side.
reverted color/grayscale workaround

reverted color/grayscale workaround which was fixed in wkhtmltopdf
0.12.1 as in
https://github.com/olivertitze/TuesPechkin/commit/58dab7982da706f07201415302f125ee1a8d975b
Merge pull request #42 from scmccart/master

Updated wkhtmltopdf to version 0.12.1, reverted color/grayscale workaround