Supporting Python3

 * Tested by py32, py33, py34 (and py27).

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Adding classifiers to setup.py

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Merge pull request #4 from mkouhei/supporting_python3

Supporting python3