Add MQTT server component

[balloob]

Description:
This PR will update the MQTT component. It will now automatically start an embedded broker if no broker config is given and connect to it. It is using the HBMQTT broker.

It will significantly lower the barrier for people that are trying out MQTT.

The default config for the broker is to allow access using user/pass homeassistant / <your api password>

Test with:

# First run HASS with mqtt component activated without any config
# In terminal 1
mosquitto_sub -V mqttv311 -t # -v
# In terminal 2
mosquitto_pub -V mqttv311 -t hello -m world

You can provide config for the embedded server using the embedded config key (see example YAML below).

To do:

• If no config given, automatically generate one based on your current HTTP configuration
• Tests
• HA Shutdown hook to properly shutdown broker

Related issue (if applicable): Fixes #1178

Example entry for configuration.yaml (if applicable):

mqtt:

# or

mqtt:
  embedded:
    # Your HBMQTT config here. Example at:
    # http://hbmqtt.readthedocs.org/en/latest/references/broker.html#broker-configuration

Checklist:

• Local tests with tox run successfully.
• TravisCI does not fail. Your PR cannot be merged unless CI is green!
• Fork is up to date and was rebased on the dev branch before creating the PR.
• Commits have been squashed.
• If the code does not interact with devices:
  • Tests have been added to verify that the new code works.

[balloob]

Instead of making this a standalone component, we should have this server be spin up by the MQTT component if no other broker specified.

Default server settings should be same password as http component.

[fabaff]

Works like a charm during a short test. I really like the idea of the coupling with the MQTT platforms.

This will definitely lower the barrier to use MQTT. It's not hard to get mosquitto/mosca running but even better if you just can start using something without the hassle of external servers/daemons.

👍

[balloob]

I am waiting for njouanin/hbmqtt#22 to be released before merging this component.

[maddox]

It will significantly lower the barrier for people that are trying out MQTT.

💃