Add unit-tests to verify that all DAO methods correctly create change
records.
Rework the change detection to use the new operation hooks, this fixes
the bugs where operations like "updateOrCreate" did not update change
records.
This PR removes the instantiation of a new change model
as models return from Change.find are already
instances of Change. This solves the duplicate Id issue #649
- Move core models `Model` and `PersistedModel` to `lib/`.
- Move `AccessContext` class to `lib/`, since it is not a model.
- Move all other built-in models to `common/models`.
This is a preparation for extracting model definitions to JSON files.
By splitting the change into multiple commits, git is able to keep track
of file moves (renames).