Deprecate LXC/LXD code path

[Victoria Martinez de la Cruz]

The LXC/LXD code is for a previous version of the container driver that was abandoned because it had distro-specific dependencies. We should just clean out the code specific to it rather than attempting to support it going forwards.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/405629

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/405629
Committed: https://git.openstack.org/cgit/openstack/manila-image-elements/commit/?id=288f6c2f97b8e7ebb12a4e2a1be18f4ae4cd5ff2
Submitter: Jenkins
Branch: master

commit 288f6c2f97b8e7ebb12a4e2a1be18f4ae4cd5ff2
Author: Victoria Martinez de la Cruz <email address hidden>
Date: Fri Dec 2 12:06:57 2016 -0300

    Removes LXC/LXD support on manila-image-elements

    The support for LXC/LXD was added as part of the initial effort
    to develop a container driver for Manila which was later on
    abandoned. Despite of that, the code in the manila-image-elements
    remained.

    This patch set removes LXC/LXD container support in
    manila-image-elements. Code-path used for generation of Docker images is
    preserved.

    This will help for the parallel effort of making
    manila-image-elements usable by end users.

    Change-Id: I99c6a7fbf2b2fb0cebb7b16d94c66f807e7ac7ef
    Closes-Bug: #1646615