Feature/ws cli (#15)

* New command line tool for transfering files / still very beta.

* add readme

* use cli11 for argument parsing

* json -> msgpack

* stop using base64 and use binary which can be stored in message pack

examples/broadcast_server/broadcast_server.cpp

@@ -47,6 +47,7 @@ int main(int argc, char** argv)
                     }
                     else if (messageType == ix::WebSocket_MessageType_Message)
                     {
+                        std::cerr << "Received " << wireSize << " bytes" << std::endl;
                         for (auto&& client : server.getClients())
                         {
                             if (client != webSocket)