Add persistent notification component (#1844)

homeassistant/components/persistent_notification.py

@@ -0,0 +1,18 @@
+"""
+A component which is collecting configuration errors.
+
+For more details about this component, please refer to the documentation at
+https://home-assistant.io/components/persistent_notification/
+"""
+
+DOMAIN = "persistent_notification"
+
+
+def create(hass, entity, msg):
+    """Create a state for an error."""
+    hass.states.set('{}.{}'.format(DOMAIN, entity), msg)
+
+
+def setup(hass, config):
+    """Setup the persistent notification component."""
+    return True