py-twython: updated to 3.7.0

3.7.0:
- Fixes for cursoring API endpoints
- Improve html_for_tweet() parsing
- Documentation cleanup
- Documentation for cursor's return_pages keyword argument
- Update links to Twitter API in documentation
- Added create_metadata endpoint
- Raise error for when cursor is not provided a callable

3.6.0:
- Improve replacing of entities with links in html_for_tweet()
- Update classifiers for PyPI

3.5.0:
- Added support for "symbols" in Twython.html_for_tweet()
- Added support for extended tweets in Twython.html_for_tweet()
- You can now check progress of video uploads to Twitter when using Twython.upload_video()

(adam)