Use openSUSE 15.0 as default, which is the latest released stable
openSUSE release. Switch to https for accessing download.o.org
as encrypted transfers should be used by default.
Remove leftovers for definitely unmaintained openSUSE 13.x images
and split into old/new leap style versioning scheme for clarity.
Change-Id: Iab129eeee2b1a2563f0f0d2cb17bbad57c068e38
In preparation for promoting the openSUSE jobs to voting ones we should
use the OpenStack mirrors. As such, the opensuse elements are modified
to make use of the DIB_DISTRIBUTION_MIRROR variable which is normally
exported by the openstack-ci-mirrors element.
Change-Id: Ie588c1c1eec13190cfb2ec718ba51f8c9878283f
