Merge pull request #5 from taivo/api-tidy

fixed formula to calculate n in rule.get_rrule. example: sept 7, 2012 sh...
Inferring calendar names from Event objects.
Merge branch 'api-tidy' of git://github.com/ixc/glamkit-eventtools into api-tidy
Fix generator's limited occurrences check to work with both timezone-aware or naive occurrence datetimes
Compatibility with latest django-mptt
Convert datetimes to the local timezone where necessary.
Fixed get_inline_instances arguments signature to work with Django 1.5
Allow the occurrence inline admin class to be easily overridden.
Fix a couple of naive datetime problems.
fix naive/aware datetime issues