log debug message if $_POST not populated

[cadorn]

See: https://github.com/firephp/firephp/blob/master/lib/Insight/Server.php#L106

See: https://groups.google.com/d/topic/devcomp/R1BGJ3iUwTU/discussion

[cadorn]

PHP has some config options to populate the $_POST variable. See: track_vars at http://php.net/manual/en/ini.core.php which must be on. Maybe this is turned off on your zend server install. Also see variables_order config option which should contain P and enable_post_data_reading must be on.