Fix recipe compile error when 'public network' is set to Ceph environment

Hi,

this patch fixes the following recipe compile error when  'public network' is set to Ceph environment.
"node" block variable overrode global node variable.

<pre>
================================================================================
Recipe Compile Error in /var/cache/chef/cookbooks/ceph/recipes/mon.rb
================================================================================

NoMethodError
-------------
undefined method `[]' for nil:NilClass

Cookbook Trace:
---------------
  /var/cache/chef/cookbooks/ceph/libraries/default.rb:84:in `get_mon_addresses'
  /var/cache/chef/cookbooks/ceph/libraries/default.rb:84:in `map'
  /var/cache/chef/cookbooks/ceph/libraries/default.rb:84:in `get_mon_addresses'
  /var/cache/chef/cookbooks/ceph/recipes/conf.rb:4:in `from_file'
  /var/cache/chef/cookbooks/ceph/recipes/mon.rb:20:in `from_file'

Relevant File Content:
----------------------
/var/cache/chef/cookbooks/ceph/libraries/default.rb:

 77:      end
 78:
 79:      mons += get_mon_nodes()
 80:      if is_crowbar?
 81:        mon_ips = mons.map { |node| Chef::Recipe::Barclamp::Inventory.get_network_by_type(node, "admin").address }
 82:      else
 83:        if node['ceph']['config']['global'] && node['ceph']['config']['global']['public network']
 84>>         mon_ips = mons.map { |node| find_node_ip_in_network(node['ceph']['config']['global']['public network'], node) }
 85:        else
 86:          mon_ips = mons.map { |node| node['ipaddress'] + ":6789" }
 87:        end
 88:      end
 89:    end
 90:    return mon_ips.uniq
 91:  end
 92:
 93:  def get_quorum_members_ips()

</pre>