Add ability to export session history as a CSV

[chris1howell]

This is an expansion of #721

Add ability to assign an RFID card to a user with a Name
Add RFID ID and Name to the session logs
Add ability to export session logs as a CSV

This would billing for stations with multiple users.

[fhteagle]

This would help the OpenEVSE to be chosen as the solution for grants that have pretty stringent reporting requirements (Charge Ahead Colorado for example).

Consider a web UI element to be able to put an identifier on a guest session that is not started via the RFID card. Use case for this would be a workplace that issues cards to its employees, but day 1 new hire, or visitor coming for a meeting needs to charge, and the reception staff enables charging without the user being issued an RFID card.