Add support for Tesla Powerwall

[markpurcell]

@angusc

I joined my home network and attempted to use the old web log in but seems that Tesla discontinued that access method, so I was unabl to try the Local-ip/api/system_status method that you shared. I now get the below screen when trying to log in via the Local IP:

They aren’t making it easy, but keep clicking though and you can still get to the local login screen.