Allow for wp-config.php to be multiple levels up (for sub-directory installs)

[Master Jake]

Currently, you can leave wp-config.php in the standard installation directory of WordPress or move it up one level. At work, we generally install WordPress in root and move wp-config.php up one level (out of the servers content directory) for security purposes. It would be nice if we could do this with sub-directory installs as well (e.g. install in /wordpress and put wp-config.php in /../ [2 levels up]).

Perhaps we could use some sort of recursive directory search that starts in the WordPress install directory and continues going up levels until it finds a wp-config.php file (if one exists). There should, of course, be some cut off level to stop searching at. I think that one level above the document root would be sufficient.

[scribu]

This has been suggested before: #12988