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/event.py

@@ -4,6 +4,7 @@ Offer event listening automation rules.
 For more details about this automation rule, please refer to the documentation
 at https://home-assistant.io/components/automation/#event-trigger
 """
+import asyncio
 import logging
 
 import voluptuous as vol
@@ -24,6 +25,7 @@ TRIGGER_SCHEMA = vol.Schema({
 })
 
 
+@asyncio.coroutine
 def async_trigger(hass, config, action):
     """Listen for events based on configuration."""
     event_type = config.get(CONF_EVENT_TYPE)