Fix 500 error from image-import call
Fix 500 error from image-import call

This patch modifies the images controller to accept a body (which
is required) for the image import call and cleans up a bit around
the request deserialization/response serialization.

Co-authored-by: Abhishek Kekane <abhishek.kekane@nttdata.com>
Co-authored-by: Brian Rosmaita <rosmaita.fossdev@gmail.com>

Change-Id: I08783e28719e63b5a4b2115b8fce135e55be460a
Closes-bug: #1708702

openstack/glance,openstack/glance,openstack/glance