Added Basic Authentication Support to Logging

[Jeffrey C. Jacobs]

I hacked the open/log/index.php to allow parse the Username and Password if Apache is configured to use Basic authentication specifically for the repos-web directory.  Digest won't work because the PHP doesn't get the password, just the realm and nonce info in the variable list so it can't send the password.  But for Basic Authentication when a correctly configured Apache (just set up the Repos-web directory exactly like SVN with AuthName, etc in the repos-web directory block) this change should work wonderfully.  I've left some debug code in if anyone wants to examine the variable in the global scope of the PHP script but the main code is just parsing the Apache Server Variables which control Username, Password, and Digest info.

Enjoy.