UnicodeDecodeError reading README.rst in setup.py

Python 3 build fails like this when run in mock (the Fedora build tool):

```
Traceback (most recent call last):
  File "setup.py", line 21, in <module>
    long_description=open('README.rst').read(),
  File "/usr/lib64/python3.2/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 8178: ordinal not in range(128)
```

You can replicate it by running:

    LC_ALL=POSIX python3 setup.py 

The fix is to explicitly read README.rst as UTF-8.