added support for VirtualHost StaticFastPath directive. 

added support for VirtualHost StaticFastPath directive to enable rewrite rule processing even if a static file is present.

issue https://github.com/facebook/hhvm/issues/1283

I am a github noob, I am unfamiliar with this codebase and my C++ is rusty. Please let me know if I have done something wrong. I have attempted to follow your guidelines, but since this is my first pull request, I may have missed something; any guidance will be appreciated. 

I am not sure how to create a test case for this fix but based on my manual testing it seems to work. 

I filled out the contributors form and agreed to the terms via the facebook link.