Upgrade paho-mqtt to 1.2.1

[fabaff]

1.2.1

• Handle unicode username and passwords correctly.
• Fix handling of invalid UTF-8 topics on incoming messages - the library now does not attempt to decode the topic - this will happen when the user accesses msg.topic in the on_message callback. If the topic is not valid UTF-8, an exception will be raised.
• Fix issue with WebSocket connection in case of network issue (timeout or connection broken).
• Fix issue with SSL connection, where latest incoming message may be delayed or never processed.
• Fix possible message lost with publish.single and publish.multiple.

Tested with the following configuration:

mqtt:
  broker: localhost

binary_sensor:
  - platform: mqtt
    name: Bathroom door
    state_topic: "home/bathroom/door"
    payload_on: "1"
    payload_off: "0"
    device_class: opening

$ mosquitto_pub -h localhost -t "home/bathroom/door" -m 1
$ mosquitto_pub -h localhost -t "home/bathroom/door" -m 0

17-04-04 10:05:52 INFO (Thread-9) [homeassistant.components.mqtt] Received message on home/bathroom/door: 1
17-04-04 10:05:52 INFO (MainThread) [homeassistant.core] Bus:Handling <Event state_changed[L]: entity_id=binary_sensor.bathroom_door, new_state=<state binary_sensor.bathroom_door=on; friendly_name=ABCDE, device_class=opening @ 2017-04-04T10:05:52.465251+02:00>, old_state=<state binary_sensor.bathroom_door=off; friendly_name=ABCDE, device_class=opening @ 2017-04-04T10:05:19.030989+02:00>>
17-04-04 10:05:55 INFO (Thread-9) [homeassistant.components.mqtt] Received message on home/bathroom/door: 0
17-04-04 10:05:55 INFO (MainThread) [homeassistant.core] Bus:Handling <Event state_changed[L]: entity_id=binary_sensor.bathroom_door, new_state=<state binary_sensor.bathroom_door=off; friendly_name=ABCDE, device_class=opening @ 2017-04-04T10:05:55.450299+02:00>, old_state=<state binary_sensor.bathroom_door=on; friendly_name=ABCDE, device_class=opening @ 2017-04-04T10:05:52.465251+02:00>>

[mention-bot]

@fabaff, thanks for your PR! By analyzing the history of the files in this pull request, we identified @balloob, @joncar and @pvizeli to be potential reviewers.