mgmt: publish GeneralStatus dataset

In ForwarderStatusManager, publish ForwarderStatus as a dataset at
/localhost/nfd/status/general.
To maintain backwards compatibility, an Interest to /localhost/nfd/status
also retrieves this dataset.

It's intentional not to update the test suite in this commit,
to illustrate that backwards compatibility is maintained.

refs #3081

Change-Id: I9b636e2e621563185303a7304be402c8221c9863
diff --git a/daemon/mgmt/forwarder-status-manager.hpp b/daemon/mgmt/forwarder-status-manager.hpp
index 57d89c8..44c112b 100644
--- a/daemon/mgmt/forwarder-status-manager.hpp
+++ b/daemon/mgmt/forwarder-status-manager.hpp
@@ -43,9 +43,14 @@
   ForwarderStatusManager(Forwarder& forwarder, Dispatcher& dispatcher);
 
 private:
+  ndn::nfd::ForwarderStatus
+  collectGeneralStatus();
+
+  /** \brief provide general status dataset
+   */
   void
-  listStatus(const Name& topPrefix, const Interest& interest,
-             ndn::mgmt::StatusDatasetContext& context);
+  listGeneralStatus(const Name& topPrefix, const Interest& interest,
+                    ndn::mgmt::StatusDatasetContext& context);
 
 private:
   Forwarder&  m_forwarder;