Bug/import

Publish was breaking if the were children references to non-existent items. Because import uses publish, this was breaking imports of some courses.

Import was breaking if a tar.gz had a directory in it w/ the same name as the root dir which occurred importing some MITx courses with manifest files.

@ormsbee @cpennington plz review
I don't understand your comment's intent. I removed the unnecessary move of the xml content tree and have import importing from wherever the course may be. If your concern is whether or not we still need course_subdir, it's still used to compute course_dir which is still an ancestor of dirpath.