Rjf/soc bug

[robfitzgerald]

addresses the bug discovered in #241. it appears that:

1. user-submitted value was correctly validated between 0 and 100
2. bug: the percent value [0,100] was being used directly to scale incoming energy (multiplying it by 100)

so the energy state would always exceed 100%. how this ended up with a state model at 100% is unclear; could be because of vehicle_ops::as_soc_percent which clips the value between 0 and 100 again. but i'm not sure.

that said, it is working:

"battery_state": {
        "type": "soc",
        "unit": "percent",
        "format": {
            "floating_point": {
                "initial": 80.0
            }
        },
        "index": 0,
        "name": "battery_state"
    },

Closes #241.

[nreinicke]

Great find, that was a subtle little bug. Thanks for fixing!