added form and list for spamfilter users.

interface/web/mail/form/spamfilter_users.tform.php

interface/web/mail/lib/lang/en_mail_user.lng

interface/web/mail/lib/lang/en_spamfilter_users.lng

interface/web/mail/lib/lang/en_spamfilter_users_list.lng

interface/web/mail/lib/module.conf.php

interface/web/mail/list/spamfilter_users.list.php

interface/web/mail/spamfilter_users_del.php

interface/web/mail/spamfilter_users_edit.php

interface/web/mail/spamfilter_users_list.php

interface/web/mail/templates/spamfilter_users_edit.htm

interface/web/mail/templates/spamfilter_users_list.htm