Change GDP_INSTALL_ROOT to GDP_ROOT, since all of the scripts in
$gdp/adm are looking for that name. An even better choice would be
GDP_RUN_ROOT, but we'll survive.
Rationalize macro names to avoid confusion and for consistency with the
base GDP code:
* GDP_ROOT => GDP_INSTALL_ROOT
* GDPROOT => GDP_SRC_ROOT
* GDPADM => GDP_ADM
Tweak systemd service files so that there will be a brief pause before
starting mqtt-gdp-gateway on reboot to let the network settle.
Tweaks for mqtt-gdp-gateway systemd service files to try to ensure that
the network is up before the gateway is started.
Create empty logs on installation; miscellaneous code cleanup and
Extensive rework on mqtt-gdp-gateway startup scripts. Not yet complete.