sanitize sensor values

src/main.cpp

@@ -227,15 +227,19 @@ void ICACHE_FLASH_ATTR sendValues() {
     root["radioactivity"] = sd.radioactivity;
   }
 
+  if (sd.voltage > 2.5 ) {
     JsonObject& voltageObject = array.createNestedObject();
     voltageObject["sensor"] = SENSOR7_ID;
     voltageObject["value"] = sd.voltage;
     root["voltage"] = sd.voltage;
+  }
 
+  if (sd.rssi != 0) {
     JsonObject& rssiObject = array.createNestedObject();
     rssiObject["sensor"] = SENSOR8_ID;
     rssiObject["value"] = sd.rssi;
     root["rssi"] = sd.rssi;
+  }
 
   root["millis"] = millis();
   root["heap"] = ESP.getFreeHeap();