Make use of io.open() with explicit file encoding in setup.py

[buckket]

When installing this module on a system with Python 3 which has no or non-utf8 locale variables set installation fails because you’re making use of the open() command in setup.py to pipe in things like README.rst and CHANGELOG.rst. This happens because Python 3 tries loading those files with the default encoding (which happens to be ASCII), and then fails with an UnicodeDecodeError.

Suggestion: Use io.open(), which is available for both Python 2 and 3 and specify the encoding of said files explicitly.

One could argue that this problem is client-sided, but I don’t see any real drawbacks fixing this on your side.

Thanks.

[pdp7]

@buckket thanks for the pull request. What is the best way for me to test the failure condition which this PR fixes?

[buckket]

Invoke pip or setup.py with a non-utf8 locale, e.g. by passing empty LANG environment variable:

$ LANG="" python3 setup.py

[pdp7]

@buckket Thanks

Fail with current master

debian@beaglebone:~/adafruit-beaglebone-io-python$ sudo bash -c 'LANG="" python3 ./setup.py install'
Traceback (most recent call last):
  File "./setup.py", line 38, in <module>
    long_description = open('README.rst').read() + open('CHANGELOG.rst').read(),
  File "/usr/lib/python3.4/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 813: ordinal not in range(128)

OK with the fix in this PR

debian@beaglebone:~/pr/adafruit-beaglebone-io-python$ sudo bash -c 'LANG="" python3 ./setup.py install'
running install
Checking .pth file support in /usr/local/lib/python3.4/dist-packages/
/usr/bin/python3 -E -c pass
TEST PASSED: /usr/local/lib/python3.4/dist-packages/ appears to support .pth files
running bdist_egg
running egg_info
writing Adafruit_BBIO.egg-info/PKG-INFO
<snip>
Installed /usr/local/lib/python3.4/dist-packages/Adafruit_BBIO-1.0.1-py3.4-linux-armv7l.egg
Processing dependencies for Adafruit-BBIO==1.0.1
Finished processing dependencies for Adafruit-BBIO==1.0.1

[pdp7]

Thanks @buckket