Merge pull request #318 from elasticsales/collection-set-triggers-change

failing test: change events should not fire on new items in Collection#set
Merge pull request #320 from elasticsales/collection-set-vs-reset

Two tests (1 failing) showing Collection reset/set should both link related objects
Use `merge: true` by default for Collection.reset. Ref #320
Simpler test added for `merge: true` on Collection.reset.

Revert "Merge pull request #320 from elasticsales/collection-set-vs-reset"

This reverts commit c31ea90071753f1f475f780ef4143229d5a28f19, reversing
changes made to 9b52eb220bb86a2da5e41c08e55b76a1f2108871.
Add a note in the change log about the changed default for `merge` on `reset`