Use standard BLOB,KEY,NACK as contentType instead of customized types

Change-Id: I792e19b8f1e2aa359605da44074fc25bf7963a9a
diff --git a/src/util/util.cpp b/src/util/util.cpp
index 31f3549..bbdf0c2 100644
--- a/src/util/util.cpp
+++ b/src/util/util.cpp
@@ -36,6 +36,8 @@
     return NDNS_BLOB;
   else if (str == "link")
     return NDNS_LINK;
+  else if (str == "key")
+    return NDNS_LINK;
   else
     return NDNS_UNKNOWN;
 }