new branch to fix event_occurences bug. Pivotal #:76544670

new branch to fix event_occurences bug.
Pivotal #:76544670, https://www.pivotaltracker.com/n/projects/982890/stories/76544670
repeating event schedule is not respecting end time limit (event.repeat_ends_on)
Fixes repeating event repeat_ends_on bug by modifying the next_occurrences function to only accept scheduled event instances before that datetime.
This variable renaming (next_occurrence_time_attr) is a temporary change to avoid confusion with the new method of a similar name.  This attribute is legacy.  It's only purpose is to hold a calculated value for event instances... which don't really belong in this class, which is primarily used for recurring event templates, and which, in my opinion,should ONLY be used for recurring event templates.
Later, I plan to remove this attribute altogether with a major refactor to simplify the Event class.  See http://www.agileventures.org/projects/websiteone/documents/events-internal-design-plans-event-templates-repeating-or-not-event-instances-and-relations-hookups-karma-and-more