cyclades: Optimize *-list commands

Use prefetch_related and select-related to importive the DB queries that
are generated by *-list snf-manage commands.

snf-cyclades-app/synnefo/api/management/commands/network-list.py

@@ -61,6 +61,8 @@ class Command(ListCommand):
     )
 
     object_class = Network
+    select_related = []
+    prefetch_related = ["subnets"]
     deleted_field = "deleted"
     user_uuid_field = "userid"
     astakos_url = ASTAKOS_BASE_URL

snf-cyclades-app/synnefo/api/management/commands/port-list.py

@@ -49,15 +49,10 @@ class Command(ListCommand):
     user_uuid_field = "userid"
     astakos_url = ASTAKOS_BASE_URL
     astakos_token = ASTAKOS_TOKEN
+    prefetch_related = ["ips"]
 
-    def get_fixed_ips(ip):
-
-        def labels((a, b)):
-            return str({"subnet": b, "ip_address": str(a)})
-
-        lista = ip.get_ip_addresses_subnets()
-        lista = map(labels, lista)
-        return " ".join(lista)
+    def get_fixed_ips(port):
+        return ",".join(port.ips.values_list("address", flat=True))
 
     FIELDS = {
         "id": ("id", "The ID of the port"),

snf-cyclades-app/synnefo/logic/management/commands/floating-ip-list.py

@@ -41,6 +41,7 @@ log = getLogger(__name__)
 class Command(ListCommand):
     help = "List Floating IPs"
     object_class = IPAddress
+    select_related = ["nic"]
     deleted_field = "deleted"
     user_uuid_field = "userid"
     astakos_url = ASTAKOS_BASE_URL