Add support for application startup events.

Allow clients to specify filters and actions that trigger
on application startup.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Change-Id: Ib36c5bab778d7c87906dd3f61a3a6e033c7ccde1
diff --git a/events.hpp b/events.hpp
index e197719..6737861 100644
--- a/events.hpp
+++ b/events.hpp
@@ -33,6 +33,7 @@
     enum class Type
     {
         DBUS_SIGNAL,
+        STARTUP,
     };
 
     virtual ~Event() = default;
@@ -47,7 +48,7 @@
      *  @param[in] t - The event type.
      */
     explicit Event(
-        const std::vector<FilterBasePtr>& filters, Type t) :
+        const std::vector<FilterBasePtr>& filters, Type t = Type::STARTUP) :
         std::vector<FilterBasePtr>(filters),
         type(t) {}
 
@@ -55,6 +56,8 @@
     Type type;
 };
 
+using StartupEvent = Event;
+
 using EventBasePtr = std::shared_ptr<Event>;
 
 /** @struct DbusSignal