The plugin now handles Authentication via Proxy and Authorisation via LDAP

The plugin has been changed in order to allow the Authorisation mechanism to use LDAP search instead of groups in informed via HTTP header.

This change was added due to the fact that Winstone limits the HTTP header to 4k only. So, organisations with a huge amount of groups would suffer with this problem.

Now the authentication is done via Reverse Proxy, as it was before, but the users can use the Advance button in order to enter the LDAP settings.