[#1640] Do not put a system icon tray as default

sflphone-client-gnome/.settings/org.eclipse.cdt.core.prefs

sflphone-client-gnome/.settings/org.eclipse.cdt.ui.prefs

sflphone-client-gnome/src/config/preferencesdialog.c

...-client-gnome/src/dbus/configurationmanager-introspec.xml

sflphone-client-gnome/src/dbus/dbus.c

sflphone-client-gnome/src/dbus/dbus.h

sflphone-client-gnome/src/main.c

sflphone-client-gnome/src/mainwindow.c

sflphone-client-gnome/src/statusicon.c

sflphone-client-gnome/src/statusicon.h

sflphone-client-gnome/src/uimanager.c

sflphone-common/src/dbus/configurationmanager-introspec.xml

sflphone-common/src/dbus/configurationmanager.cpp

sflphone-common/src/dbus/configurationmanager.h

sflphone-common/src/managerimpl.cpp

sflphone-common/src/user_cfg.h