asetkey: permit des-cbc-md5 and des-cbc-md4 keys

asetkey: permit des-cbc-md5 and des-cbc-md4 keys

A DES key is a DES key.  Permit importing CRC, MD5 and MD4
when using non-MIT keytab support.

Add a special error message that specifies what principal
name, kvno, and enctype were being searched for when the
error is KRB5_KT_NOTFOUND.

Change-Id: Ie04e86fc5516064a67d7804cc47f2e27a30ea7ea
Reviewed-on: http://gerrit.openafs.org/4459
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>