Combine before_validations into one private method
Remove paperclip
Back out consolidation of before_validations
Clean up event_spec

* Split associations, validations, callbacks into groups
* Remove unnecessary constant reference
* Remove DelayedJobSpecHelper when not used
* Remove unused tests
* Prefer `==` to `eq` in RSpec assertions
Space out groups of associations
Shorten long validation message
Move callbacks into the same spec group

* Write missing spec for inviting the owner
@wip in process