Adding node start observer.

rai/core_test/node.cpp

@@ -1296,3 +1296,22 @@ TEST (node, no_voting)
 	}
 	ASSERT_EQ (0, node1.network.confirm_ack_count);
 }
+
+TEST (node, start_observer)
+{
+    rai::node_init init;
+    auto service (boost::make_shared <boost::asio::io_service> ());
+    rai::alarm alarm (*service);
+	auto path (rai::unique_path ());
+	rai::logging logging (path);
+	rai::work_pool work (std::numeric_limits <unsigned>::max (), nullptr);
+    auto node (std::make_shared <rai::node> (init, *service, 0, path, alarm, logging, work));
+	auto started (false);
+	node->observers.started.add([&started] ()
+	{
+		started = true;
+	});
+	node->start ();
+	ASSERT_TRUE (started);
+	node->stop ();
+}

rai/node/node.cpp

@@ -1552,6 +1552,7 @@ void rai::node::start ()
 	active.announce_votes ();
 	port_mapping.start ();
 	add_initial_peers ();
+	observers.started ();
 }
 
 void rai::node::stop ()

rai/node/node.hpp

@@ -378,6 +378,7 @@ public:
 	rai::observer_set <rai::vote const &, rai::endpoint const &> vote;
 	rai::observer_set <rai::endpoint const &> endpoint;
 	rai::observer_set <> disconnect;
+	rai::observer_set <> started;
 };
 class vote_processor
 {