Align measurement entities between the hardware (and hardware mock) and the app

[szokolimatyas]

I saw:

server.send(200, "text/plain", sendRAW(temperature, humidity, pressure, altitude, wifiStrength)); 

in the hardware code. The server expects (temperature, humidity, pressure, battery, timestamp). The timestamp will be generated by the app, but I have a few requests/questions:

• Is the battery level from the hardware, or the app @noratanX ?
• Please use application/json as a content-type in the hardware and in the mock, so I can easily deserialize it @SandorBalazsHU.
• If there is no need for it in the backend, remove the altitude field.
• Sync the hardware mock with the actual output of the hardware units.

[szokolimatyas]

Also, wifiStrength is unused at the moment, so that could be removed.

[szokolimatyas]

Basically I need a: { temp: Float, pressure: Float, humidity: Float, battery: Float (percentage)} json, with application/json Content-Type.