[krbdev.mit.edu #1512] afs_string_to_key fails to work with etype_info2

[Sam Hartman via RT]

On the server side, the server must send out etype_info2 with a
s2kparams of 1 for AFS salts.  At least if the enctype is DES-based.

On the client side, the code needs to call afs_string_to_key if the
s2kparams of 1 are used.