nginx 0.6.31 release

Changes with nginx 0.6.31                                        12 May 2008

   *) Bugfix: nginx did not process FastCGI response if header was at the
      end of FastCGI record; bug appeared in 0.6.2.
      Thanks to Sergey Serov.

   *) Bugfix: a segmentation fault might occur in worker process if a file
      was deleted and the "open_file_cache_errors" directive was off.