pkcs7-md5 and pkcs7-sha1 micalg values

I propose that the micalg parameter for multipart/signed messages with
the "application/pkcs7-signature" protocol be defined as pkcs7-md5 and
pkcs7-sha1 for the MD5 and SHA-1 digest algorithms respectively.  I
further propose that any future digest algorithms that are supported for
S/MIME keep the "pkcs7-" prefix.

Comments?

Blake