need to filter out non-own metadata. Also we need to clone draft content
update some unit tests on clone_course
add more testing. Assert that metadata is properly cloned and that draft content is cloned as well
address PR feedback
Merge pull request #609 from edx/fix/cdodge/clone-course-needs-to-save-only-own-metadata

[STUD-608] django-admin clone_course needs to properly copy metadata as well as draft content