- Add an ephemeral self-signed Attestation Cert to NSSToken
- A new one is generated at each call to Register; this is allowed by the
protocol, and avoids fingerprinting if the NSSToken is in use.
- This now passes at https://u2fdemo.appspot.com/
MozReview-Commit-ID: Aq61MuX9oSD
--HG--
extra : transplant_source : %C1%00n6%22%01%E7q%B4/%D8-%C5W%D4%E6%86%14%25%C2
J.C. Jones