ESPHome Fix intermediary state published

[OttoWinter]

Fixes esphome/issues#426

Description:

There was an issue with ESPHome entities where they would publish old states when coming back online because of some internal mechanics.

Scenario:

1. Device powers up, sends state 23.0 to HA - HA creates entity with state 23.0
2. Device powers down, HA sees this and sets availability to false. State: unavailable.
3. Device powers up again, HA sees this again and sets availability on all entities to true again. A state update is scheduled and the old state of 23.0 is published
4. A few milliseconds later, the device reports the new state of 18.0. HA state update: 18.0

This PR basically disables the state update scheduling in step 3. In hindsight, it's an oversight in the communication protocol that the initial state is not sent together in the packet with the entity info, but now it can't be changed that easily.

Related issue (if applicable): fixes #

Pull request with documentation for home-assistant.io (if applicable): home-assistant/home-assistant.io#<home-assistant.io PR number goes here>

Example entry for configuration.yaml (if applicable):

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist