core: drop std::function and ndn::Exclude from common.hpp, add ndn::optional

Change-Id: Ie3983d8b6f9929430efd8ada8d942e3f95755cd4
diff --git a/daemon/face/protocol-factory.hpp b/daemon/face/protocol-factory.hpp
index fe3f1f8..74dbde7 100644
--- a/daemon/face/protocol-factory.hpp
+++ b/daemon/face/protocol-factory.hpp
@@ -137,7 +137,7 @@
   struct CreateFaceRequest
   {
     FaceUri remoteUri;
-    ndn::optional<FaceUri> localUri;
+    optional<FaceUri> localUri;
     FaceParams params;
   };