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/tools/nfdc/execute-command.hpp b/tools/nfdc/execute-command.hpp
index 09f28d5..2d8a716 100644
--- a/tools/nfdc/execute-command.hpp
+++ b/tools/nfdc/execute-command.hpp
@@ -43,6 +43,7 @@
 using ndn::Face;
 using ndn::KeyChain;
 using ndn::nfd::ControlParameters;
+using ndn::nfd::ControlResponse;
 using ndn::nfd::Controller;
 
 /** \brief context for command execution