[libvirt] Add UID/GID support to virt-sandbox-service

[dwalsh at redhat.com]

This patch set is adding support for UID/GID/USERNAME/USERDIR for use with openshift
containers

Also fixes virt-sandbox-service to not complain if the destdir has been precreated.

Finally we also do not want excess processes running withing containers (/bin/sh).

[sandbox PATCH 1/3] Add UID/GID support for use with interactive
[sandbox PATCH 2/3] Only create the destination path if it does not
[sandbox PATCH 3/3]  Do not run a shell within a lxc container by