Add classifiers to setup.py
Add classifiers to setup.py

Closes #150

arthurian/python-oauth2,squirro/python-oauth2,jackiekazil/python-oauth2,simplegeo/python-oauth2,joestump/python-oauth2,jgsogo/python-oauth2,tygpatton/python-oauth2,InnovativeTravel/python-oauth2,alekskorolev/python-oauth2,CestusMagnus/python-oauth2,edworboys/python-oauth2,CentricWebEstate/python-oauth2