Generate numpy arrays exported with labels for the test set

To test the model, we have a development set of 7 samples of actual trolls the needs to labeled them by hand, to create a development set using the same distribution as the real inputs. The raw audios are stored in `data/test`, within the downloaded dataset.

For now, I'm using the same synthesized data to test de model (not a good approach, so, if you can, please send your contribution with the labeled dev set)

https://docs.scipy.org/doc/numpy-1.13.0/reference/routines.io.html