Munweather uses non-public API

[Gudahtt]

Munweather is currently broken, because the OpenWeatherMap API it uses seems to be no longer public. It now requires an API key.

We should probably be checking to ensure the HTTP request returned something useful, for one thing. And then returning a nicer error message if not. But we also need to use a different API - one that isn't broken.

[karoliina]

I can't get the free version of their API key to work, so I'm switching to another API.