Switching to v3 streams enables testing of Xenial HWE and HWE-edge kernels and the squashfs root which MAAS 2.3 uses. - Add v3 streams URL - Introduce two attributes, ephemeral_ftype, target_ftype to determine which files are needed for the ephemeral environment and which for the target - Add kflavor and subarch filters to streams query and release classes to support kernel variants: ga, hwe, hwe-edge. We're currently only testing subarch 'generic' and ignoring 'low-latency' - When testing with hwe and hwe-edge, emit a kernel configuration to curtin to ensure we install the matching kernel in the target image - Make sure vmtests append collect scripts to the base class parameter so all tests run the BaseVM collect_scripts (dpkg-query) - Introduce new release classes, XenialGA, XenialHWE and XenialEdge Note, XenialGA replaces the general Xenial release class, and that not all test-cases run Xenial HWE/Edge kernels; most of the storage ones do. - Booting from a squashfs image requires some changes - publish the squashfs image and boot VMs with root=URL (except trusty) - utilize overlayfs to keep the ephemeral environment pristine and use the squashfs image as a the curtin install source. - Add some boot parameters to the ephemeral environment to enable networking, including DNS for package installation. - Use BOOTIF= parameter for multi-nic vmtests to ensure we only bring up one nic for ephemeral networking. Sometimes multiple nics would come online and then cause networking hiccups which prevented installs from completing. - Modify vmtest storage configurations for disks to all use a 'serial' attribute. Currently we use 'disk-X' as the serial value where X increments from 'a' -> 'z' as the test needs. - jenkins-runner now prints additional information about what images are found and available. - tools/launch - modify --append to allow multiple parameters to grow the array. - fix bug in --publish which prevented more than a single file being published - allow PUBURL to be expanded in root-arg - add a 'boot-image' parameter which is exported to the VM with a serial number to provide a consistent path to the device, /dev/disk/by-id/virtio-boot-disk - drop '2G' boot size parameter to boot disks, instead allow qemu-img to default to the size of backing image.