mgmt+tools: rework FacePersistency handling in faces/create and faces/update

1. enable changing persistency in faces/update command
2. reject faces/create request if the face already exists
3. nfdc changes to support the above

Change-Id: I659906da846608a42a768f08fb110ceee1a947a7
refs: #3232
diff --git a/daemon/mgmt/face-manager.hpp b/daemon/mgmt/face-manager.hpp
index 9a8c503..b7991b8 100644
--- a/daemon/mgmt/face-manager.hpp
+++ b/daemon/mgmt/face-manager.hpp
@@ -103,6 +103,9 @@
                         const ControlParameters& parameters,
                         ControlParameters& response);
 
+  static ControlParameters
+  collectFaceProperties(const Face& face);
+
 PUBLIC_WITH_TESTS_ELSE_PRIVATE: // StatusDataset
   void
   listFaces(const Name& topPrefix, const Interest& interest,