Python3 support

[chrisdonahue]

Need to update nesmdb package to support Python 3.5

Current obstacles:

• Print statements do not use parentheses
• Need to fix relative imports
• Dependency on cPickle (fix by using six?)
• Initial VGM processing depends heavily upon old binary string semantics. Python 3 reads binary files as byte arrays; Python 2.7 reads binary files as strings which I cast to a list to simplify reading/writing. There should be some easy way to force Python 3 to use the old semantics but I'm not sure how.

Contributions from someone with more Py3 experience would be welcome <3