Add list_network_attachments.

Currently, the server side isn't accepting the GET arguments,
but this should pass them correctly.

haas/cli.py

@@ -491,10 +491,21 @@ def port_detach_nic(switch, port):
     url = object_url('switch', switch, 'port', port, 'detach_nic')
     do_post(url)
 
+@cmd
+def list_network_attachments(network, project):
+    """List nodes connected to a network
+    <project> may be either "all" or a specific project name.
+    """
+    url = object_url('network', network, 'attachments')
+
+    if project == "all":
+        do_get(url)
+    else:
+        do_get(url, data={'project':project})
+
 @cmd
 def list_nodes(is_free):
     """List all nodes or all free nodes
-    
     <is_free> may be either "all" or "free", and determines whether
         to list all nodes or all free nodes.
     """