Allow Owners to transfer projects between namespaces
Allow for changing of project namespaces via the API
I believe that if the UI allows a user to perform an action, they should be able to do so via the API for parity. This doesn't seem to be the case for changing project namespaces -- using GitLab.com for example. This is useful for when you want to move many repositories in bulk.
Links / references
/label ~"feature proposal"