Explicit utf-8 encoding for long_description

[guzmud]

cf. https://packaging.python.org/guides/making-a-pypi-friendly-readme/ and pip install codec issues (the, quite regular yet a bit mysterious, conflict in pip with locales encoding and reading. Quick google search, with debian or docker keywords, will provide more info.).

[coveralls]

Coverage remained the same at ?% when pulling 446e6fe on guzmud:patch-1 into d1d4a0f on blag:master.

[rrbb014]

I'm Window10 user
When i used "$ pip install humanhash3" for install, it occured UnicodeDecodeError because of 'cp949'.
It need to merge..

[nturley]

+1 my salt-stack environment couldn't use this package because of this issue.