Vehicle interface, availability, data changes

Added Vadim's VehicleInterface and availability proposal.
Added ButtonEvent, DrivingMode and NightMode to data spec
moved vehiclecommon to this spec. fixed some html errors
Merge pull request #36 from tripzero/master

Looks OK. It'd be better to merge first and fix later if there is an issue. Otherwise, it'll be hard to merge the other commit because of conflicts.