In old implementation, version-check always get the latest versions
rather than versions for certain release. it is useless for stable
branch. And it parses from tarballs.openstack.org site, which is
very slow.
In this new implementation, version-check gets versions from
openstack/releases repo, which is faster and accurate. It also support
get versions for certain OpenStack release. For example, get the Ocata
latest release version.
./verion-check.py --openstack-release ocata
Closes-Bug: #1554337
Change-Id: Ie8951625817d82f38cf820cf9bd44ae447e2eb75