Python 3 support

[eliangcs]

#45 already fixed a partial Python 3 issues, but to support Python 3 fully, we have to:

• Fix code where the tests are failed on Python 3
• Update .travis.yml to make it test against Python 3.x
• Update setup.py so people on PyPI knows vcli supports Python 3

[jhurliman]

Is this being worked on?

[eliangcs]

@jhurliman sorry, no. I don't spend time maintaining vcli anymore as I no longer use it that often.