Send access card number to attendance API if available

[kberzinch]

If the app reads a plastic BuzzCard with both a GTID and access number encoded, provide both values to the attendance API

Server-side support is part of RoboJackets/apiary#4594

[evan10s]

Manual entry by GTID won't include the access card number, sounds like that's fine though?

[kberzinch]

Yes, that's fine, a GTID is still the primary identifier for attendance.