contrib: add dbus-c++ to support systems which do not package it
Issue generated from Tuleap's migration script. Originally submitted by: Stepan Salenikovich (ssalenik)
dbus-c++ is not packaged on all systems (eg: it is missing on freeBSD) and the "official" sourceforge repo seems no longer maintained:
However, it is still maintained on GNU/Linux systems and possibly now at this repository:
We should add it to the Ring contrib systems so that users can easily compile it on systems where it is not packaged.
Additionally, it would be nice to provide alternative Ring building instructions in order to be able to build the Ring gnome as one process with the daemon if the users does not whish to use dbus.