Add HateSpeech Corpus for Polish
This PR adds a HateSpeech Corpus for Polish, containing offensive language examples.

- **Homepage:** http://zil.ipipan.waw.pl/HateSpeech
- **Paper:** http://www.qualitativesociologyreview.org/PL/Volume38/PSJ_13_2_Troszynski_Wawer.pdf