feature request: add ability to get a objects location via its container

[sjoeboo]

We have a large number of blades systems we create as "Servers", with a container representing the chassis that contains them all (server_chassis object type). We would like to be able to retrieve one of these objects via get_depot, and have its location as defined by its containers location (since the child object really has no "location" aside form being inside the container)