Adding in boost::asio support

main starts a thread that keep a global io_service object
running and makes sure it is stopped when everything else is
stopped.

pglab/GlobalIoService.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include <memory>
+#include <boost/asio.hpp>
+
+std::shared_ptr<boost::asio::io_service> getGlobalAsioIoService();