Add links to PyPI and Crate.io in README file
Add links to PyPI and Crate.io in README file

pombredanne/django-simple-history,luzfcb/django-simple-history,pombredanne/django-simple-history,emergence/django-simple-history,luzfcb/django-simple-history,treyhunner/django-simple-history,emergence/django-simple-history,treyhunner/django-simple-history