make tests run with latest pytz, also related fix

datetimes were still not properly expanded and they old way the timezone
information was applied in the tests didn't catch this

this should fix #82 on github
event from string fix

year should now be correctly inferred if the event is created by a
string like '25.10.2013 18:00 26.10. 20:00 Event Description'

this should properly fix #83