doesn't make any sense to render xml here.
light refactoring of EventsController.
move #duplicates controller action to mixin.
remove mocks from EventsController#create and #update tests.
extract duplication from EventsController#create and #update.
make this more robust against order and reloading.
factor out some private methods in EventsController#create_or_update.
extract Event::Saver from EventsController#create_or_update.
minor refactor of Event::Saver.
Merge pull request #127 from botandrose/refactor_events_controller

Refactor EventsController