get the library working on py3k (#4)

Here is my proposed fix for #4: Python 3.x support. Mostly just print statement upgrades, the requests library needed an upgrade, and I used the `unicode_literals` future import for Python 2.x to treat literals as unicode by default. That screwed up the `__all__` import in 2.x, which I worked around by wrapping the names in `str()`