This example shows how it is possible to use a custom type on the DBus.

Because the DBus can only handle primitive types, we essentailly make a 
DBus typedef for a struct timeval.  The server will return two integers,
which we then put into a struct timeval on our side.  

When we add a custom type, we need to know what the signature of it is;
in our case, it is two ints.

Note that this example may not work with all DBus bindings; the server
sends back two ints, essentially two return values.  Other bindings may
not have the capability to handle more than one return value.
