Enable CDI by default when MP Config usage is detected in the deployment.

Currently users are forced to add empty beans.xml to the deployment every time they want to use MP Config - e.g. in simple servlet scenario

@WebServlet("/")
public class HelloServlet extends HttpServlet {
    @Inject
    @ConfigProperty(name = "port_number")
    Integer port;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        resp.getWriter().println("Value of port: " + port);
    }
}

MP Config without CDI makes no sense to me. MP Config subsystem should be able to ensure CDI is enabled. CCing manovotn brian.stansberry