Add include_locations kwarg to nova.image.API.get()

To avoid feature envy from image backends that need image location URIs,
functionality of nova.image.glance._get_locations() is moved into
nova.image.glance.show() and exposed via a new include_locations kwarg
to the nova.image.API.get() method, which, when True, simply includes a
collection of location links when the image has them.

blueprint rbd-clone-image-handler
Co-Authored-By: Jay Pipes <jaypipes@gmail.com>

Change-Id: I5118013aa24f68520dee806c24265f2808a90588
Merge "Add include_locations kwarg to nova.image.API.get()"