Prozlach/unittests

Unittests for check-zonesync
I see that you uses assert{True,False} a lot but remember that in case of fail it will give an error message (`AssertionError: False is not true`) that will not explain anything and you will have to analyze tests source to find out what is broken.

mock library has a build-in `assert_called_*` functions that would fit better here.

For example, you could change:
```
self.assertTrue(ScriptStatusMock.notify_agregated.called)
```

into:

```
ScriptStatusMock.notify_agregated.assert_called_once()
```