weather: forecast up to 10 days

This service needs api key. For now I put it straightly into the url
It will need to be replaced, like in perl with {{ENV_APIKEY}} , but not sure if python supports this. Gonna look at it deeply.

Signed-off-by: Adrian Matejov <a.matejov@centrum.sk>
I'm really not sure how do we go about this in the future but we'll in the end need some installation procedure that will say that hey, you need an API key, insert it into the config.

For now, could you please check if there is `apikey` in `self.config` and throw an exception if there is not?

Moreover, can you use `APIKEY` or `API_KEY` instead of `apikey` so that we can see right away that it actually is a constant.