fix setup.py 'ascii' codec can't decode byte 0xc3 in position 9191
fix setup.py 'ascii' codec can't decode byte 0xc3 in position 9191

Observed problem running 'python setup.py install' with Python 3.6.3
Fixed by using explicit 'utf8' encoding reading README.rst

See https://gist.github.com/jq170727/a628bddb9e9591fa10c96c719c17f086
for details to reproduce and demonstrate fix.

jdowner/gist,jdowner/gist