Add activation, item_updater and version

Implement part of functions of Activation, ItemUpdater and Version.

Tested: Upload a dummy PSU tarball, and verify the activation object is
        created with expected ExtendedVersion, and the object is deleted
        when Delete is invoked.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: I7b9d29f46914ace93d27a715b32c80957e88a0aa
diff --git a/src/activation.cpp b/src/activation.cpp
index e69de29..8bfed0b 100644
--- a/src/activation.cpp
+++ b/src/activation.cpp
@@ -0,0 +1,27 @@
+#include "activation.hpp"
+
+namespace phosphor
+{
+namespace software
+{
+namespace updater
+{
+
+namespace softwareServer = sdbusplus::xyz::openbmc_project::Software::server;
+
+auto Activation::activation(Activations value) -> Activations
+{
+    // TODO
+    return softwareServer::Activation::activation(value);
+}
+
+auto Activation::requestedActivation(RequestedActivations value)
+    -> RequestedActivations
+{
+    // TODO
+    return softwareServer::Activation::requestedActivation(value);
+}
+
+} // namespace updater
+} // namespace software
+} // namespace phosphor