Allow for CN/username of 64 characters (fixes off-by-one)

Allow for CN/username of 64 characters (fixes off-by-one)

This is an alternative patch to fix the issue reported in trac #515 by
Jorge Peixoto. Instead of increasing the TLS_USERNAME_LEN define, do +1 at
the relevant places in the code.

Also see Jorge's original patch and the discussion on the maillinglist:
http://thread.gmane.org/gmane.network.openvpn.devel/9438

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <54F8CC9B.9040104@karger.me>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9508
Signed-off-by: Gert Doering <gert@greenie.muc.de>