change strings of SPF result, exim conditions names

unify the results of spf condition according to:
RFC (RFC4408, draft-ietf-spfbis-4408bis-21 as future proposed standart ),
libspf2 ( http://www.libspf2.org/docs/html/spf__response_8h.html#f783f446ad824eb439b0230a7c3f6739 )