tracking a charge session

[robfitzgerald]

create new ReportTypes for CHARGE_PLUG_IN_EVENT, CHARGE_PLUG_OUT_EVENT, and CHARGE_SESSION_EVENT.

create reports from

• CHARGE_PLUG_IN_EVENT: DispatchStation. _enter_default_terminal_state (line 100)
• CHARGE_PLUG_OUT_EVENT: ChargingBase/ChargingStation exit and _enter_default_terminal_state methods
• CHARGE_SESSION_EVENT: created in the EventfulHandler by watching for for plug in events, storing them, and then watching for the corresponding plug out event plug out events. creates a new event from them.