Add support for bad_words Issue:#246

[ujwal-narayan]

Added support for bad_word_ids as discussed in Issue#246

• Modified GENSettings to allow users to provide a list of bad words/phrases
• Modified generate_text in happy-transformer/happy_generation.py
• Added a test_case test_bad_words in tests/test_gen.py
• Updated documentation and examples in docs/1-text-generation/3-settings.md

[EricFillion]

Thanks for adding this feature! I really appreciate how you put in effort to write in-depth tests and to update the documentation. Here are some suggestions

[ujwal-narayan]

Thank you so much for your feedback! I've updated the pull request with the requested changes :)

[EricFillion]

Thanks for adding this feature! I'll create a new release within a week.