Add (currently failing) tests related to fixing #191
Docs: add a section on the event queuing
toJSON: if set to just the id, also add ids for 'unfound' models. Should fix #191.
test showing change events shouldn't fire too often
test: a collection parse function shouldn't break fetching of parent model
failing test: 'Deep reverse relation starting from a collection'
test: Keep keySource value around if model doesn't exist