Set umask when starting Passenger/httpd

Explicitly set umask 002 when starting Passenger/httpd. This ensures
the correct tmp directory permissions are used when Passenger creates
new directories in response to shutdown and restart signals.

Resolve bugs:
  - https://bugzilla.redhat.com/show_bug.cgi?id=1080397
  - https://bugzilla.redhat.com/show_bug.cgi?id=1080357