poke: code modernization and cleanup

Change-Id: Ia0d5f0b1bc495636f8fac127bec735cc35af66a7
diff --git a/manpages/ndnpeek.rst b/manpages/ndnpeek.rst
index 9468889..0b6683e 100644
--- a/manpages/ndnpeek.rst
+++ b/manpages/ndnpeek.rst
@@ -63,4 +63,4 @@
 
 Send Interest for ``/app1/video`` and print the received payload only::
 
-    ndnpeek -p ndn:/app1/video
+    ndnpeek -p /app1/video