Updated dbus-cxx library

[Robert Middleton]

Hi all,

For those of you who are C++ people, I've spent the last ~2-3 years
upgrading dbus-cxx to be a full DBus implementation and I now feel
that I have something that is ready for wider use.  Before I
officially release though, I wanted to see if there was anybody here
that may be able to give feedback on how things stand now.

This /should/ also be a fully thread-safe implementation at this point
as well, so if anybody has a multithreaded program to test it out with
that'd be awesome.  I also have hooks for both GLib and Qt, so it
should be easy to utilize with these libraries.

Here's the branch: https://github.com/dbus-cxx/dbus-cxx/tree/dbus-cxx-2

-Robert Middleton