Fingerprint: Add Show instance for easier debugging

Signed-off-by: Austin Seipp <aseipp@pobox.com>
Fingerprint: Add getFileHash

Signed-off-by: Austin Seipp <aseipp@pobox.com>
Fix -Werror failure in GHC.Fingerprint

Signed-off-by: Austin Seipp <aseipp@pobox.com>