add security.level for php-fpm #65935

https://bugs.php.net/bug.php?id=65935

It went something like this:

  Someone asked for suexec like functionality, a gid/uid check, which I implemented.
  Some other people said can we do more.
  Remi pointed out that suexec is much more

http://httpd.apache.org/docs/2.2/suexec.html

  suexec is loads, and restrictive, all the time.

So for php-fpm *only* I implemented a security level to give a bit of power to the user in configuring their security.

Lastly ... SECURE ALL THE THINGS !!!