Add device_class to image_processing (home-assistant#6186)

* Add image_processing device_class

* Fix comments

* address comments

homeassistant/components/image_processing/__init__.py

@@ -28,6 +28,11 @@
 
 SCAN_INTERVAL = timedelta(seconds=10)
 
+DEVICE_CLASSES = [
+    'alpr',        # automatic license plate recognition
+    'face',        # face
+]
+
 SERVICE_SCAN = 'scan'
 
 ATTR_CONFIDENCE = 'confidence'

homeassistant/components/image_processing/microsoft_face_identify.py

@@ -90,6 +90,11 @@ def state(self):
 
         return state
 
+    @property
+    def device_class(self):
+        """Return the class of this device, from component DEVICE_CLASSES."""
+        return 'face'
+
     @property
     def state_attributes(self):
         """Return device specific state attributes."""

homeassistant/components/image_processing/openalpr_local.py

@@ -94,6 +94,11 @@ def state(self):
                 plate = i_pl
         return plate
 
+    @property
+    def device_class(self):
+        """Return the class of this device, from component DEVICE_CLASSES."""
+        return 'alpr'
+
     @property
     def state_attributes(self):
         """Return device specific state attributes."""