Added key fingerprint and key type fields to uploader registration
request model, so that MyData can use a public key fingerprint
to query whether its private key matches the public key in the
registration request record.  If not (for example, user
accidentally deleted their private key, so a new key-pair
needs to be generated), the fingerprint can be used to identify
the mismatch.  Fingerprints are almost always displayed alongside
the key type (usually RSA or DSA), so a key type field is
included alongside the fingerprint field.