treewide: Cleanup signal emission

Don't emit properties changed prior to interfaces added.

Change-Id: I7f88b8052a323ca49ce9f16fe446596213e3fdb5
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/ethernet_interface.hpp b/src/ethernet_interface.hpp
index e617eae..a1e9975 100644
--- a/src/ethernet_interface.hpp
+++ b/src/ethernet_interface.hpp
@@ -96,7 +96,7 @@
     void addStaticNeigh(const NeighborInfo& info);
 
     /** @brief Updates the interface information based on new InterfaceInfo */
-    void updateInfo(const InterfaceInfo& info);
+    void updateInfo(const InterfaceInfo& info, bool skipSignal = false);
 
     /** @brief Function used to load the ntpservers
      */