MQTT convert to async (#6064)

* Migrate mqtt to async

* address paulus comment / convert it complet async

* adress paulus comment / remove future

* Automation triggers should be async

* Fix MQTT async calls

* Show that event helpers are callbacks

* Fix tests

* Lint

homeassistant/components/automation/state.py

@@ -4,6 +4,7 @@ Offer state listening automation rules.
 For more details about this automation rule, please refer to the documentation
 at https://home-assistant.io/components/automation/#state-trigger
 """
+import asyncio
 import voluptuous as vol
 
 from homeassistant.core import callback
@@ -34,6 +35,7 @@ TRIGGER_SCHEMA = vol.All(
 )
 
 
+@asyncio.coroutine
 def async_trigger(hass, config, action):
     """Listen for state changes based on configuration."""
     entity_id = config.get(CONF_ENTITY_ID)
@@ -97,6 +99,7 @@ def async_trigger(hass, config, action):
     unsub = async_track_state_change(
         hass, entity_id, state_automation_listener, from_state, to_state)
 
+    @callback
     def async_remove():
         """Remove state listeners async."""
         unsub()