setup.py not python2 compatible
```
$ python --version
Python 2.7.15rc1
$ python setup.py 
Traceback (most recent call last):
  File "setup.py", line 12, in <module>
    long_description = open('README.rst', encoding = 'utf8').read(),
TypeError: 'encoding' is an invalid keyword argument for this function
```

`encoding` is not valid to [open()](https://docs.python.org/2/library/functions.html#open) in python2.