Fixes #6

This fixes the issue #6, this is before the fix:
```sh
> s.getPosition(date,50.5,30.5).azimuth * (180/Math.PI)
-143.25764539039318
```
and after, all in degrees, because I'm unable to read radians :)

```
> s.getPosition(date,50.5,30.5).azimuth * (180/Math.PI)
36.742354609606814
```

tests updated too