[ticket/11337] Run functional tests on travis using nginx and php-fpm.

PHPBB3-11337
[ticket/11337] php-fpm.conf is no longer owned by root.

PHPBB3-11337
[ticket/11337] Silence nginx config file writing.

PHPBB3-11337
[ticket/11337] Only run functional tests on 5.3.19 or higher. No FPM otherwise.

There is no php-fpm for PHP 5.3.3. Make sure PHP version is at least 5.3.19,
which is what 5.3 is currently aliased to.

PHPBB3-11337
[ticket/11337] Abort setup-webserver.sh script when an error occurs.

PHPBB3-11337