brightness based on sun elevation

[emkookmer]

I've replaced the static brightness with a template based brightness. The template takes the sun elevation, minimum brightness and maximum brightness, then it calculates the relative brightness between the min/max based on the elevation

The User must configure the latitude/longitude to get a correct elevation, (default is Greenwich)

í've also addes the webserver component which enables debugging and changing of the min/max brightness, but this can also be done from HA