This commit consists of:
1) Ability for the netconf client to retrieve schemas metadata from
   the netconf server
2) Ability for the netconf server to retrieve specific yang schema from
   the netconf server
3) Netconf says Happy New Year 2017

Change-Id: I6552224707607ca6cc1397f2fbf193503bb116a3
diff --git a/netconf/constants.py b/netconf/constants.py
index e59a73e..332ec16 100644
--- a/netconf/constants.py
+++ b/netconf/constants.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 #
-# Copyright 2016 the original author or authors.
+# Copyright 2017 the original author or authors.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -19,6 +19,9 @@
 
 	SSH_SUBSYSTEM = "netconf"
 
+	# Send message max size
+	MAXSSHBUF = 1024 * 1024
+
 	# Secure credentials directories
 	# TODO:  In a production environment these locations require better
 	# protection.  For now the user_passwords file is just a plain text file.
@@ -80,6 +83,8 @@
 
 	#tags
 	NC = "nc"
+	VOLTHA = 'voltha'
+	NCM = "ncm"
 	RPC = "rpc"
 	RPC_REPLY = "rpc-reply"
 	RPC_ERROR = "rpc-error"
@@ -96,3 +101,11 @@
 	MESSAGE_ID = "message-id"
 	XMLNS = "xmlns"
 	DELIMITER = "]]>]]>"
+
+	NS_MAP = {
+		'nc': 'urn:ietf:params:xml:ns:netconf:base:1.0',
+		'voltha': 'urn:opencord:params:xml:ns:voltha:ietf-voltha',
+		'ncm': 'urn:ietf:params:xml:ns:yang:ietf-netconf-monitoring'
+	}
+
+