rib: turn RibUpdate into an aggregate

And move it together with RibUpdateList and RibUpdateBatch.
Also remove a few unused functions from RibEntry.

Change-Id: Id4f79fda27d3bffb8411e2a95c24154e2cb80c4f
diff --git a/daemon/mgmt/rib-manager.cpp b/daemon/mgmt/rib-manager.cpp
index d9331e5..41f9925 100644
--- a/daemon/mgmt/rib-manager.cpp
+++ b/daemon/mgmt/rib-manager.cpp
@@ -40,7 +40,6 @@
 
 namespace nfd {
 
-using rib::RibUpdate;
 using rib::Route;
 
 NFD_LOG_INIT(RibManager);
@@ -156,11 +155,7 @@
     NFD_LOG_TRACE("Scheduled unregistration at: " << *route.expires);
   }
 
-  RibUpdate update;
-  update.setAction(RibUpdate::REGISTER)
-        .setName(name)
-        .setRoute(route);
-  beginRibUpdate(update, done);
+  beginRibUpdate({rib::RibUpdate::REGISTER, name, route}, done);
 }
 
 void
@@ -170,15 +165,11 @@
   NFD_LOG_INFO("Removing route " << name << " nexthop=" << route.faceId <<
                " origin=" << route.origin);
 
-  RibUpdate update;
-  update.setAction(RibUpdate::UNREGISTER)
-        .setName(name)
-        .setRoute(route);
-  beginRibUpdate(update, done);
+  beginRibUpdate({rib::RibUpdate::UNREGISTER, name, route}, done);
 }
 
 void
-RibManager::beginRibUpdate(const RibUpdate& update,
+RibManager::beginRibUpdate(const rib::RibUpdate& update,
                            const std::function<void(RibUpdateResult)>& done)
 {
   m_rib.beginApplyUpdate(update,