In this changeset, I added the "audit" and the "strategy "ObjectField
which can either be loaded by setting the new "eager" parameter as True
or not loaded (as before) by setting it to False.
The advantage of introducing this eager parameter is that this way,
we can reduce to a minimum the overhead of DB queries whenever the
related object fields is not actually needed.
Change-Id: Ieca6fa438cbf2267f5ae2ea0d059b2953e65076b
Partially-Implements: blueprint watcher-versioned-objects
060c369838