Add option to override sensor ID

closes #5

Author: corny

config.yml.default

@@ -1,6 +1,9 @@
 luftdaten:
   enabled: true
 
+  # Override the serial derived from the CPU
+  # sensor: 012345
+
 influxdb:
   enabled:  false
   url:      'http://example.com:8086/write?precision=s&db=sensors'

main.py

@@ -134,7 +134,7 @@ def run():
     m.sendInflux()
 
 
-sensorID  = "raspi-" + getSerial()
+sensorID  = config['luftdaten'].get('sensor') or ("raspi-" + getSerial())
 starttime = time.time()
 
 while True: