templating the icon for phoebus navigator

templates/phoebus_navigator.desktop.j2

@@ -3,6 +3,6 @@ Type=Application
 Terminal=false
 Name=Navigator OPI
 Comment=Launch Control System Studio Phoebus with only the Navigator OPI
-Icon=/opt/ess-cs-studio-phoebus-4.6.521/css-512x512.png
+Icon={{ phoebus_icon }}
 Categories=ESS
 Exec=sh -c "cd; rm -rf .phoebus/memento; /usr/local/bin/phoebus -resource /opt/opis/30-Operator/00-Navigator/navigator.bob"