Add support for callbacks

Callbacks are the response in the PDM 'trigger->response' model.
Add general support for implementing callbacks and implement
a log to systemd journal using that framework.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Change-Id: I8bead5368ee5472a02b47e8bba9e9df3a1f346bc
diff --git a/src/propertywatchimpl.hpp b/src/propertywatchimpl.hpp
index 46799ed..6e957ae 100644
--- a/src/propertywatchimpl.hpp
+++ b/src/propertywatchimpl.hpp
@@ -32,10 +32,6 @@
     {
         return;
     }
-    else
-    {
-        alreadyRan = true;
-    }
 
     // The index has a flat layout which is not optimal here.  Nest
     // properties in a map of interface names in a map of object paths.
@@ -107,6 +103,8 @@
             }
         }
     }
+
+    alreadyRan = true;
 }
 
 template <typename T, typename DBusInterfaceType>