IOS-XE 17.x removed the default NETCONF namespace assumption.

Be explicit about where <filter> is defined.

Reported by:	cromulon-actual (#22)
Clue bat by:	einarnn

Author: jclarke-csco

NC-get-config/NC-get-config.py

@@ -52,7 +52,7 @@
                          device_params={'name':"csr"})
 
     hostname_filter = '''
-                      <filter>
+                      <filter xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
                           <native xmlns="http://cisco.com/ns/yang/Cisco-IOS-XE-native">
                           </native>
                       </filter>