[#80 Added some new tests ]
[#80] Fixed tests for delete_user_from_event.rb
[#80] Add functionality to CalendarApp

Allow user who is not event owner to unsubscribe from event
Cover with tests
[#80] Fix merge conflict
[#80] Fixed test destroy_user_spec
Merge branch 'delete_user_from_event' of github.com:gotar/Internship-calendar-API into delete_user_from_event
Merge pull request #64 from gotar/delete_user_from_event

[#80] Delete user from event