try to fallback to unittest2 if using an older python version
try to fallback to unittest2 if using an older python version

Python 2.6 doesn't have unittest.TestCase.assertIsNotNone, among
others.  If we don't have it, try to import unittest2 as unittest.

maxcountryman/rauth,arifgursel/rauth,litl/rauth,isouzasoares/rauth,maxcountryman/rauth,isouzasoares/rauth,arifgursel/rauth,litl/rauth,arifgursel/rauth