Fixes repeating event repeat_ends_on bug by modifying the next_occurrences function to only accept scheduled event instances before that datetime.

Pivotal #: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.
the `Delorean#time_travel_to` should really go in a `before(:each)` block