nginx-0.3.57-RELEASE import

    *) Feature: the $ssl_client_serial variable.

    *) Bugfix: in the "!-e" operator of the "if" directive.
       Thanks to Andrian Budanstov.

    *) Bugfix: while a client certificate verification nginx did not send
       to a client the required certificates information.

    *) Bugfix: the $document_root variable did not support the variables in
       the "root" directive.