node+transport: Improving async operations and error reporting

All operations, including connect are fully async

Change-Id: I6c28c4f883d3aa10efbc4af939cf09e0e865c574
diff --git a/include/ndn-cpp/node.hpp b/include/ndn-cpp/node.hpp
index ef1d40e..4092330 100644
--- a/include/ndn-cpp/node.hpp
+++ b/include/ndn-cpp/node.hpp
@@ -134,6 +134,11 @@
   void
   onTransportError();
 
+  struct ProcessEventsTimeout {};
+  
+  static void
+  fireProcessEventsTimeout(const boost::system::error_code& error);
+
 private:
   class PendingInterest {
   public: