Newer versions of cliff and stevedore use importlib rather than
setuptools to work with entry points. Replace any references to
"setuptools' entry points mechanism" with "Python's entry points
mechanism".
Change-Id: Iae36155685ee37ab5e38a0c173110a5ece33d05d
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>