* Fix arwn platform discover_sensors
The discover_sensors function can return either singletons or a list
of sensors. However the consumer was always expecting a list. This
fixes it to work in both cases.
* Add custom icons to arwn sensors.
This adds some custom icons for different kinds of weather sensors
that the arwn platform returns. Makes it a little easier to see what's
going on.
This adds a sensor component that builds sensors based on the arwn
project (https://github.com/sdague/arwn). This uses a 433mhz receiver
to collect weather data and publish it over mqtt in a well defined
schema, which home-assistant can display as sensors.
Pascal Vizeli
Sean Dague
Fabian Affolter