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/dhcp_configuration.cpp b/src/dhcp_configuration.cpp
index d421111..154bbee 100644
--- a/src/dhcp_configuration.cpp
+++ b/src/dhcp_configuration.cpp
@@ -49,10 +49,10 @@
         conf.setFile(newest_file.path());
     }
 
-    ConfigIntf::dnsEnabled(getDHCPProp(conf, "UseDNS"));
-    ConfigIntf::ntpEnabled(getDHCPProp(conf, "UseNTP"));
-    ConfigIntf::hostNameEnabled(getDHCPProp(conf, "UseHostname"));
-    ConfigIntf::sendHostNameEnabled(getDHCPProp(conf, "SendHostname"));
+    ConfigIntf::dnsEnabled(getDHCPProp(conf, "UseDNS"), true);
+    ConfigIntf::ntpEnabled(getDHCPProp(conf, "UseNTP"), true);
+    ConfigIntf::hostNameEnabled(getDHCPProp(conf, "UseHostname"), true);
+    ConfigIntf::sendHostNameEnabled(getDHCPProp(conf, "SendHostname"), true);
     emit_object_added();
 }