first update

- updateIntervalSeconds : the weather information will not be updated
very often, so please refresh information manually!
- setup(unsigned int targetWOEID, char temperatureUnit, unsigned int
updateIntervalSeconds)
- setup(unsigned int targetWOEID, char temperatureUnit)
- setup(unsigned int targetWOEID)
- update()

+ setup(unsigned int targetWOEID, char temperatureUnit = ‘c’) : default
+ refresh() : instead of the function “update()”