Add httpserver to contrib

.. see http://stefanfrings.de/qtwebapp/index-en.html

.. this is a lightweight web server to allow GC to
   provide webservices.

.. we will be providing web services on localhost to
   enable R integration.

.. we will use web services to standardise the
   interface to provide something we can use in R
   but also anything else at a later date.

.. gcconfig.pri contains $$HTPATH that points to
   the location of the code, if it is not set then
   the web server is not compiled in.

httpserver/httpglobal.cpp

@@ -0,0 +1,7 @@
+#include "httpglobal.h"
+
+const char* getQtWebAppLibVersion()
+{
+    return "1.5.8";
+}
+