Little check button on audio settings GTk to enable ringtones

sflphone-gtk/src/configurationmanager-glue.h

sflphone-gtk/src/configwindow.c

sflphone-gtk/src/dbus.c

sflphone-gtk/src/dbus.h

src/dbus/configurationmanager-glue.h

src/dbus/configurationmanager-introspec.xml

src/dbus/configurationmanager.cpp

src/dbus/configurationmanager.h

src/global.h

src/managerimpl.cpp

src/managerimpl.h

src/user_cfg.h