[COOK-2307] Added monitored_client_interface functionality.
Move attribute under server.
Should use n['ipaddress'] instead of node['ipaddress']
Move default['nagios']['server']['monitored_client_interface'] to attributes/server.rb
Add url for ohai network_addr plugin.
Update ohai network_addr plugin info.
Remove extraneous <%
Missing else clause.
Create a warning in the chef logs if a node doesn't have monitored_client_interface defined.
Fixed accidental reversion while rebasing.