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>
Could you move all the lines that take data from "r" to method returning string? Maybe it could be even possible to give this method a format string? So that all those lines would become: `return self._format_output(r, u'Day: {daytemp}\u2103  Night: {nighttemp}\u2103  Wind: {wind}km/h  ({metric})').encode('utf-8')` or something similar?

@mrshu: What do you think?