Don't try to re-save events' time information after batch requests. Refactor the session_test and make sure new events are generated for each test.
Make a unit test more forgiving.
Factor some code out of session class - now calendar instances know how to structure calendar metadata from xml elements. Remove references to master_time_zone - it's not needed for a general-purpose library like this. Make it easier for users to add their own test data. Now, it's managed through a data file. Update README accordingly. .gitignore a data file.