Add serial number verification for BootNotifications

[wfvining]

See requirement B01.FR.11 (Part 2, page 45). This is only applicable to security profile 3.

[wfvining]

Not putting this into ocpp_station. I'd like to keep all the security-related functionality in its own module/process. This probably means creating an ocpp_station_security server that can be used for anything security related (e.g. when a boot notification is received the ocpp_station calls ocpp_station_security:verify_serialnumber(StationId, SerialNumber). This will both keep from cluttering the ocpp_station module and make it easier to test and validate critical security functionality.