Deprecate yumpkg in favor of yumpkg5

This incorporates the repo management functions from yumpkg5 (which did not use the yum/rpm python API anyway) directly into yumpkg5.

**NOTE: This means that the code exists in both files now and edits to the repo management functions in yumpkg.py will not make it into yumpkg5.py, and vice-versa. This should be taken into consideration when merging any future yumpkg changes.**