Gather topology element info to TopologyImpl

- Moved all the self-contained topology elements (*Event) to
  TopologyImpl. (ONOS-1651)
  Now {Switch, Port, Link, Host}Impl is just a handler attached to
  TopologyImpl.
- BugFix: TopologyManager.addHost(HostEvent)
  HostEvent could be pushed to reorder queue multiple times,
  if multiple attachment point was given.
- BugFix: TopologyManager.{addLink, removePort}
  Properly handle if Host attachment point was removed as side-effect.
- BugFix: Copy HostEvent#lastSeenTime
- BugFix: Event instance notified to listeners (api*Events) should be
  the event which was/will be in the replica. (TopologyManager)
- Added/Modified debug log in TopologyManager so that log will be in
  same format for each event type.
  "{Added, Update, Removed} <Self-contained>"
- Removed backdoor method and use TestUtils instead.

Change-Id: If053d6f11f39574a188e7a52cb6194114f8afe5d
diff --git a/src/main/java/net/onrc/onos/core/topology/HostEvent.java b/src/main/java/net/onrc/onos/core/topology/HostEvent.java
index 4c8f78d..c35764e 100644
--- a/src/main/java/net/onrc/onos/core/topology/HostEvent.java
+++ b/src/main/java/net/onrc/onos/core/topology/HostEvent.java
@@ -59,6 +59,7 @@
         super(original);
         this.mac = original.mac;
         this.attachmentPoints = new ArrayList<>(original.attachmentPoints);
+        this.lastSeenTime = original.lastSeenTime;
     }