[isf-wifidog] Client gets blank page when trying to login to RADIUS based network

[Mark Dammer]

Here is my solution for the problem:
Line 176 in AuthenticatorRadius.php was meant to fix a possible security 
hole in the radius implementation, but it completely breaks the 
authenticator code as it returns a non-object.
This line looks like this:
User :: setCurrentUser(null);//This should fix a security hole if using 
an empty username.  I didn't have time.....
Commenting out this line of code solves the problem with the blank 
pages. But do it at your own risk - I do not know how serious the 
security vulnerability mentioned in the comment after the code is.

happy radius, Mark