Py3 testing

[higs4281]

Code refactor for Python 3 and linting compliance.
I'm still fiddling with some csv tests and the coverage drop, but t
The beast can be observed.

[edited: imports combined]
It occurred to me that I do a variation of this little dance in a number of places, and it would be nice to just do it once:
import six
if six.PY2:
from unicodecsv import DictReader
else:
from csv import DictReader

[coveralls]

Coverage remained the same at 100.0% when pulling f30e32f on py3-testing into 09eab0c on master.

[willbarton]

Whew. Finally made a read-through. The changes all make sense to me and the tests pass for me! Heroic effort! A few comments follow.

[willbarton]

This change makes me laugh.

[higs4281]

@willbarton Thank you for the review, and for catching the python_2_unicode_compatible omissions!