Non ASCII character in README.rst causes invalid package

[hugoduncan]

There is … in README.rst.

Collecting graphene>=1.0.dev (from -r /requirements.txt (line 11))
  Downloading graphene-1.0.dev20160918041239.tar.gz
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-build-evvbdzqi/graphene/setup.py", line 45, in <module>
        long_description=open('README.rst').read(),
      File "/root/.pyenv/versions/3.5.1/lib/python3.5/encodings/ascii.py", line 26, in decode
        return codecs.ascii_decode(input, self.errors)[0]
    UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 636: ordinal not in range(128)