Expect a minimal length for the fingerprint

[vsund]

Line 274 allows users to use (really) weak identifiers in their profile.

For example gpg_fetch_key("<contentUrl from profile>", "") goes through without problems.

Fix would be to expect at least 16 (or more) chars of the key id in a users profile (better the full fingerprint I think).

[jcnelson]

Sure, can do :)

[jcnelson]

7489d3a