Allow both lowercase and uppercase RuuviTag ID's in configuration

[jussisallinen]

I had following initial configuration and spent quite a bit of time trying to figure out why every RuuviTag was showing 0% in Homebridge Accessories:

       {
            "accessory": "Ruuvitag",
            "name": "Living Room",
            "id": "D37E812920CC"
        },
        {
            "accessory": "Ruuvitag",
            "name": "Wine Fridge",
            "id": "EEA0CAEA0755"
        }

Finally I figured out I might need to try lowercase ID's just to eliminate it out as cause of 0% readings and that did the trick:

     {
           "accessory": "Ruuvitag",
           "name": "Living Room",
           "id": "d37e812920cc"
       },
       {
           "accessory": "Ruuvitag",
           "name": "Wine Fridge",
           "id": "eea0caea0755"
       }