Changed temporary IDs so they don't conflict with the UUID spec so you can use UUIDs as permanent IDs.
Update CHANGES.md
Give credit for #117
Merge branch 'uuid'
Use the appropriate callback when using offline storage

Blanket success was incorrect. For example, when fetching and id that was never cached locally,
the error callback should be used.

Related: #94
Merge branch 'master' into mocha
Test callbacks