Changes to permit dockerization of mqtt-gdp-gateway. Still a bit crude.
Another cut at trying to get mqtt-gdp-gateway running under Docker.
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
Installation/Configuration scripts update: try to guess if the system
uses upstart or systemd; other installation cleanup.
Moved /uhb/mqtt-gateway* to /uhb/mqtt-gateway/*