Add in-message cli_request/cli_reply API

This new CLI API is meant to replace the
cli_request/cli_reply that uses shared memory.

PS: checkstyle -- *hate*

Change-Id: I6318f8f6b9be2c2398b49dac9e2193c1998ea724
Signed-off-by: Ole Troan <ot@cisco.com>

vpp-api/python/vpp_papi/vpp_papi.py

@@ -99,6 +99,12 @@ def disconnect():
     logging.info("Disconnected")
     return rv
 
+# CLI convenience wrapper
+def cli_exec(cmd):
+    cmd += '\n'
+    r = cli_inband(len(cmd), cmd)
+    return r.reply[0].decode().rstrip('\x00')
+
 def register_event_callback(callback):
     event_callback_set(callback)