Usage of default values if no gpio in config

__init__.py

-from config import dht_gpio
+try:
+    from config import dht_gpio
+except ImportError:
+    dht_gpio = None
+
 try:
     import Adafruit_DHT as dht
 except ImportError:
         #
         # DHT22
         #
-        if dht is None:
+        if dht is None or dht_gpio is None:
             h = -17.3
             t = -125.7
         else: