Update sphinx extension logging
Update sphinx extension logging

Sphinx 1.6 deprecated using the application object to perform logging
and it will be removed in the upcoming 2.0 release. This updates our
extensions to use the recommended sphinx.util.logging instead.

Change-Id: I3b44e096c62a081e195ea22bc953d1752d7ff4b7
Signed-off-by: Sean McGinnis <961eeb09b6d45516665e15b82e013282c4faf575@gmail.com>

openstack/cinder,mahak/cinder,openstack/cinder,mahak/cinder