Switch to fastcgi.conf on nginx >= 1.6.1

In accordance with
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=718639 nginx PHP5
configuration will now check the installed nginx version and correctly
pick old 'fastcgi_params' or new 'fastcgi.conf' configuration file to
include in the server configuration for PHP5 applications.
Merge pull request #1 from drybjed/update-fastcgi-params

Switch to fastcgi.conf on nginx >= 1.6.1