Remove the old security model.

This change removes all the implementation and a bulk of the interfaces
for the old veyron security model.

The PublicID type is still left in veyron2/security/model.go, it will be
removed once I remove a few unnecessary usage of it in the store and
wspr repositories.

Change-Id: I639047c4dc6ca70d3f4019f6556ba93bb9a9dced
diff --git a/runtimes/google/ipc/stream/proxy/proxy.go b/runtimes/google/ipc/stream/proxy/proxy.go
index 683ea0c..8e9c509 100644
--- a/runtimes/google/ipc/stream/proxy/proxy.go
+++ b/runtimes/google/ipc/stream/proxy/proxy.go
@@ -77,7 +77,7 @@
 	}
 }
 func (s *server) String() string {
-	return fmt.Sprintf("RoutingID %v on process %v (VCI:%v ID:%v)", s.RoutingID(), s.Process, s.VC.VCI(), s.VC.RemoteID())
+	return fmt.Sprintf("RoutingID %v on process %v (VCI:%v Blessings:%v)", s.RoutingID(), s.Process, s.VC.VCI(), s.VC.RemoteBlessings())
 }
 
 // servermap is a concurrent-access safe map from the RoutingID of a server exporting itself