Config Entry migrations

[andrewsayre]

Description:

Implements basic Config Entry migration functionality:

• Migration occurs during entry setup (prior to calling component.async_setup_entry)
• Compares version of the entry to the version in the ConfigFlow and if they do not match determines migration is needed.
• Components define async_migrate_entry(hass, entry) -> bool where the entry can be directly updated and will be saved. Return True if migration was successful or not needed.
• New entry state ENTRY_STATE_MIGRATION_ERROR represents failure to migrate.
• If user interaction is required (i.e. a new required field has been added) - remove the entry and start a new config flow.
• If user action is required (but not in config flow), raise a persistent notification indicating what must be done

[balloob]

I think that if a new entry is needed, that can be implemented by initiating a new flow which, on completion, removes the old flow. That's how we do it for Hue if a new bridge is registered on a new IP, all other entries for that bridge are killed.

[andrewsayre]

@balloob @MartinHjelmare This is ready for final review. Build is passing--it's seems to coveralls that's the issue. I have a pending SmartThings component improvement to get in before the next release so people don't have to re-authorize the SmartApp, which is dependent on this.

[MartinHjelmare]

Looks good! @balloob should merge.

[MartinHjelmare]

You can try rebasing on latest dev. Coveralls seems flaky.

[andrewsayre]

You can try rebasing on latest dev. Coveralls seems flaky.

I can try that tonight if not already merged. :) .