Old Yubikey-specific code and settings need to be removed

[Stuart Metcalfe]

The old, experimental, Yubikey code and settings are still lurking in at least the schema.py and main.cfg files in both trunk and the sso-config branch. We can't remove the section independently as it's defined as 'fatal=True' so we'll need to correlate removal and and deployment. There may also be removable Yubi code in other areas and in the templates. This has all been superseded by the OATH 2-factor code so should be removed at some point.

[Dimitri John Ledkov (xnox)]

How are you going to support multiple devices?
Yubikey supports sending token id, OATH by itself does not.

[Stuart Metcalfe (stuartmetcalfe)]

@dmitrij.ledkov: We loop through each device to match the entered token. Also, Yubico have *just* added a feature to their ykpersonalize tool (currently in an experimental PPA) to support IDs in OATH tokens (www.openauthentication.org/oath-id) and we will aim to support that in our implementation.