IPPOWundergroundWeatherServiceImpl reworked, new tests

Refactored/redesigned how IPPOWundergroundWeatherServiceImpl is going to work. Now has a void method as the public interface, with two callback blocks. The intention is that the ViewController code will here specify which method should be called that will then go on to start loading in the Haiku (using other code for that) and finally update the screen.

The tests now use Kiwi. I 'think' they are working. But at the moment, I still need to write the test which handles the scenario where the call to Wunderground API fails, and the appropriate fail block is then invoked.

Finally, the other changes in the code are due to introducing the Uncrustify plugin for Xcode to format the code in a common style. (rather than going off and using AppCode for example)

Signed-off-by: Ippoippo <ippoippo_software@ippoippo.net>