App RTCProximity Sensor
AppRTCProximitySensor manages functions related to the proximity sensor in the AppRTC demo. On most device, the proximity sensor is implemented as a boolean-sensor. It returns just two values "NEAR" or "FAR". Thresholding is done on the LUX value i.e. the LUX value of the light sensor is compared with a threshold. A LUX-value more than the threshold means the proximity sensor returns "FAR". Anything less than the threshold value and the sensor returns "NEAR".