Add TMPDIR global to vm install script for security purposes
For safety purposes, /tmp is usually mounted as noexec. This generates an error during installation of VMmanager, as Docker requires some files within this directory to be executable. Therefore, please add a TMPDIR global to the Docker script, to avoid having to (temporarily) remount /tmp as executable. This is a security issue.
See https://github.com/docker/compose/issues/1339 for reference.