centos based images have wrong label info,
these changes fix own image's name and build-date.
Change-Id: I1d13f8f386c8db12b5fbe5f8ecbbf9e3fbb4ba1c
Closes-Bug: #1680341
Zun uses wsgi to start process.
Rework zun-base image to make use of wsgi.
Create zun user with macros to maintain static uids.
Zun compute need root to connect docker
Change-Id: Idd417e1b804148543ee5f403a836fa1f3e6f7fb0
Closes-Bug: #1682142
Use LABEL instruction instead of MAINTAINER (deprecated) instruc-
tion as suggested by Docker's official dockerfile guide.
docs.docker.com/engine/reference/builder/#maintainer-deprecated
Closes-Bug: #1683652
Change-Id: Ie87a1ddf31aefcd0b623fd2837d78de420e76898