Don't check kpasswd reply address

Don't check the address of the kpasswd server when parsing the reply
we received from it.  If the server's address was modified by a proxy
or other network element, the user will be incorrectly warned that the
password change failed when it succeeded.  The check is unnecessary as
the kpasswd protocol is not subject to a reflection attack.

[ghudson@mit.edu: edit commit message]

ticket: 7886 (new)