Streisand: Travis CI broken - replace PPA with Snap installed LXD

[cpu]

Expected behavior:

CI runs nightly, creates a Streisand LXC and provisions it.

Actual Behavior:

CI fails all tasks, failing to add the LXC PPA:

 TASK [Install LXC ppa] *********************************************************
 fatal: [localhost]: FAILED! => {"changed": true, "cmd": ["add-apt-repository", "ppa:ubuntu-lxc/lxd-stable"], "delta": "0:00:00.957898", "end": "2018-01-20 20:38:01.876233", "failed": true, "msg": "non-zero return code", "rc": 1, "start": "2018-01-20 20:38:00.918335", "stderr": "", "stderr_lines": [], "stdout": "Cannot add PPA: 'ppa:ubuntu-lxc/lxd-stable'.\nPlease check that the PPA name or format is correct.", "stdout_lines": ["Cannot add PPA: 'ppa:ubuntu-lxc/lxd-stable'.", "Please check that the PPA name or format is correct."]}
     to retry, use: --limit @/home/travis/build/StreisandEffect/streisand/tests/development-setup.retry

Steps to Reproduce:

Invoke a build.

[cpu]

Made some progress on this today but after a few hours sunk into fixing the problem I'm still not 100% there.

Tl;dr - We missed a deprecation notice for the PPA: https://github.com/lxc/lxd/issues/4176 The official recommendation is to use the backported packages (too old for us in 14.04/travis) or install using snap.

@alimakki did some initial work to try and get a snap based LXD setup working in CI but ran into a unix socket error. I've made more progress since then and have LXD installed from snap working in CI and successfully booting a 16.04 container. The issue now is that the Ansible LXD connection to provision the container is failing.

Excited to resume fighting this soon :sob: but for today I'm out of time :ghost: :clock1:

[cpu]

Managed to solve the last outstanding issue last night. Fix is out in PR #1156