Person should have a picture parameter

[jvmonjo (Josep Vicent Monjo i Agut)]

Since person component is ment to be the main source of Truth for positioning, it should have a picture parameter to be able to show it in the UI.

[Robban]

https://github.com/home-assistant/architecture/issues/151#issuecomment-464605113

[jvmonjo (Josep Vicent Monjo i Agut)]

Thanks for pointing out this issue. Subscribed.