Merge pull request #1112 from balloob/switch-template

First cut of switch.template

homeassistant/components/sensor/template.py

@@ -94,10 +94,7 @@ class SensorTemplate(Entity):
 
         def _update_callback(_event):
             """ Called when the target device changes state. """
-            # This can be called before the entity is properly
-            # initialised, so check before updating state,
-            if self.entity_id:
-                self.update_ha_state(True)
+            self.update_ha_state(True)
 
         self.hass.bus.listen(EVENT_STATE_CHANGED, _update_callback)