Update dns.py

A previous commit broke nsd restarting.  This fixes that change.

management/dns_update.py

@@ -98,7 +98,7 @@ def do_dns_update(env, force=False):
 
 	# Tell nsd to reload changed zone files.
 	if len(updated_domains) > 0:
-		shell('check_call', ["/usr/sbin/nsd-control", "reload"])
+			shell('check_call', ["/usr/sbin/service", "nsd", "restart"])
 
 	# Write the OpenDKIM configuration tables for all of the mail domains.
 	from mailconfig import get_mail_domains