Add unique IDs to entities

[pnbruckner]

This allows some entity attributes to be set via the UI's Entities page.

Closes #72

[pnbruckner]

The first commit has not been thoroughly tested. Also, this integration is due for some serious updating, so there should be much more to come. If anyone gives this a try, even with just these minimal changes, I'd appreciate any feedback, good or bad.

[RafaelSchridi]

Working great so far! (had to censor my location, its just a town name behind there)

[RafaelSchridi]

I'm not so sure this is a good idea, this would give sensors like "sensor.daylight" as a unique_id right?

Maybe force a prefix when not using a namespace? or no unique_id if you're not using a ns?
not sure what the right approach is.

[RafaelSchridi]

Placed this at the wrong method, should have been a comment on the abstract method of sensor.py

[pnbruckner]

If namespace was not specified, then the unique ID (in your example) would be "Daylight". There really shouldn't be more than one daylight sensor configured with no namespace (or with a given namespace, for that matter), so that shouldn't be a problem.

The whole idea of using entity_namespace is to allow having more than one of a given type of sensor (usually with different location information), such that the resulting entity ID is predictable. (If namespace wasn't used, two daylight sensors, say with two different sets of location values, would have unpredictable entity IDs. E.g., one would be sensor.daylight and the other would be sensor.daylight_2, and which is which can't be predetermined. At least, that's what I would expect to happen. I haven't tried it recently.)

The actual value of the unique ID isn't important, just that it's unique for all sensors of the same domain (i.e., sensor or binary_sensor) and for the same platform (i.e., sun2.) The unique ID isn't even displayed to the user.

But what is really important is coming up with a method to determine a unique ID based on the config file, such that it doesn't change when HA restarts, and is very unlikely to change if the configuration is changed. This is important because it "maps" the config file entry to the entity registry entry. As long as the entity_namespace value isn't changed, the mapping will stay the same.