Bring wkhtmltopdf into CiviCRM

The wkhtmltopdf on google code that is linked from civicrm is unmaintained. The current version gives segmentation faults on several popular linux distributions, such as centos 6. The maintained version is hosted on git, but binaries are not provided. That means that if anyone wants to setup wkhtmltopdf on their server to integrate with civicrm, they need to compile a binary of it themselves. This is a painstaking process the has the potential to drive people away from civicrm.

The default performance provided by dompdf is severely lacking and completely unacceptable for production use. wkhtmltopdf is now licensed under the LGPL, so we should be able to integrate it and distribute it with civicrm without any licensing issues: https://github.com/antialize/wkhtmltopdf/blob/master/COPYING

Distributing wkhtmltopdf together with civicrm would add a HUGE amount of ease of use and consistency. It would give civicrm production ready pdf reporting out of the box, rather than requiring an expert to configure it as is currently the case.