mgmt+face: move protocol-specific face creation checks into protocol factories

Also brought implementation of faces/create in line with design

refs #3731

Change-Id: I4f48079136b42c7fdbd4fdfba37116d2565f9dc1
diff --git a/daemon/face/unix-stream-channel.cpp b/daemon/face/unix-stream-channel.cpp
index 5b56c6a..85416fd 100644
--- a/daemon/face/unix-stream-channel.cpp
+++ b/daemon/face/unix-stream-channel.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
- * Copyright (c) 2014-2015,  Regents of the University of California,
+ * Copyright (c) 2014-2016,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -126,7 +126,7 @@
 
     NFD_LOG_DEBUG("[" << m_endpoint << "] Accept failed: " << error.message());
     if (onAcceptFailed)
-      onAcceptFailed(error.message());
+      onAcceptFailed(500, "Accept failed: " + error.message());
     return;
   }