Also upload sdist to PyPi

fixes #39, fixes #18

Author: JoshData

README.md

@@ -393,6 +393,7 @@ To release:
 
     pip3 install twine
     rm -rf dist
+    python3 setup.py sdist
     python3 setup.py bdist_wheel
     twine upload dist/*
     git tag v1.0.XXX # replace with version in setup.py