Allow specifying recursion depth when building images

Kolla image build tool go through the image dependency chain, to make sure every image in the path are built in order

However, either in dev or real production case, sometimes there's a small fix needed for the final image (e.g swift-object-replicator), but don't want touching the entire dependency chain (s.g swift-object-replicator -> swift-object-base -> swift-base -> openstack-base).

Because overtime, parent images can change due to upstream package update, source update etc. For the purpose of small change in children image (swift-object-replicator), it will cost too much time to build and potentially can introduce breaking changes).

The idea is to allow user specify depth level (similar to git clone --depth), so that once specified, build tool never go deeper beyond this level.