Allow access if HTTP authorization took place

Wow... I'm not clear on why this request involves 14 previous commits since last April. I only meant to request a single change to a single file. Maybe I need to rebase at some point...?

Anyway, I think this would be a nice feature to have so you could securely use this tool on a live web server. From what I understand, if either `$_SERVER['REMOTE_USER']` is not empty or the key 'Authorization' exists in the array returned by `apache_request_headers()`, that should indicate successful HTTP authorization. Although it's possible that the server authenticated the user in a way that those values would not detect. Also, there could still be a way to spoof those values, but no method immediately comes to mind. What do you say?