Add python3 compatibility
Add travis build
revert Python-3 adaption for iso8601 module as this was pulled in from upstream and should not be modified
small refactorings after python 3 changes
update TODO file, Python 3 is done now :-)
fix travis configuration
fix test skipping on Python 2.6: the skipTest() method was only introduced in Python 2.7 so we use nose's implementation