Python3

Fixes a number of Python 3 incompatiblities (resolves #51 ). This patch tests against py26, py27, py33, and py34. All tests are currently passing on tox. 
The `print()` function was backported to py26 and py27, so the __future__ import is unnecessary. It is only necessary to import when the newer `print()` functions features (such as the `file` and `end` parameters) are used.