When researching the systemd tmpfiles.d implementation I discovered the
effort to standarize on /usr/share/factory as a generic factory defaults
for Linux systems. This patch adds a small example factory.cfg file
that is installed as /usr/share/factory/cfg/startup-config.cfg. The
tmpfiles.d backend will then install it as /cfg/startup-config.cfg if
that file is missing at boot. Confd does the rest to bootstrap our
(by default) empty sysrepo db with this startup-config.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>