dbus-cxx 0.1.2 released

This release fixes a few minor bugs. The generator now uses the ::DBus:: namespace rather than DBus:: to allow the use of the namespace DBus in other nested hierarchies without ambiguity. The m4 generated files have also been cleaned up to eliminate several no-op compiler warnings. The documentation has been updated to reflect the fact that dbus-cxx is now available in Fedora directly and also includes a short synopsis on dbus-cxx-xml2cpp. Finally, an autoconf macro has been added (ax_dbus_cxx_xml2cpp.m4) to streamline using dbus-cxx-xml2cpp in downstream projects.