- Version bump to 2.15.1 (bsc#1097115)
* elements: pip-and-virtualenv: Handle openSUSE Leap 15
* Allow to rebuild arbitrary images
* Replace the ubuntu-minimal trusty test with a bionic one
* Remove non-maintained ubuntu-core element
* elements: zypper-minimal: Add support for openSUSE Leap 15.X
* Add Ubuntu 18.04 support
* Remove duplicate GRUB command line entry
* rpm-distro: set the contentdir yum var
* Trivial: update url to new url
* Fixes add-apt-keys in dpkg element
* Add pip cache cleanup to pip-and-virtualenv
* pip-and-virtualenv: fix install-pip when centos-release-openstack is enabled
* Stop using slave_scripts/install-distro-packages.sh