Support HarmonyHub names other than "Harmony"

[denis-stepanov]

Currently this name is hard-coded, but Harmony app allows changing it. So, to be correct, we need to provide an option to configure it.

[denis-stepanov]

There's also automatic discovery, so at very minimum we could check it and use the first hub available.

$ curl -s -S http://localhost:8282/hubs/
{"hubs":["harmony"]}
$ 

[denis-stepanov]

Another related feature is that there could be reasons to run HarmonyAPI server on a different machine. In this case localhost would change to something else. And, to avoid flipping all Harmony devices instead of just TV, one needs to be more specific with the path. So maybe a better idea would be to allow user specifying a base URL, of a type http://<host>:8282/hubs/<hubname>/commands/...

[denis-stepanov]

I lost access to Harmony Hub device, so all changes related to it will be cancelled.