Add option for DNS nameservers to quantum_subnet module

cloud/quantum_subnet

@@ -89,6 +89,11 @@ options:
         - The ip that would be assigned to the gateway for this subnet
      required: false
      default: None
+   dns_nameservers:
+     description:
+        - DNS nameservers for this subnet, comma-separated
+     required: false
+     default: None
    allocation_pool_start:
      description:
         - From the subnet pool the starting address from which the IP should be allocated
@@ -202,6 +207,7 @@ def _create_subnet(module, quantum):
             'enable_dhcp':     module.params['enable_dhcp'],
             'tenant_id':       _os_tenant_id,
             'gateway_ip':      module.params['gateway_ip'],
+            'dns_nameservers': module.params['dns_nameservers'],
             'network_id':      _os_network_id,
             'cidr':            module.params['cidr'],
     }
@@ -215,6 +221,10 @@ def _create_subnet(module, quantum):
         subnet.update({'allocation_pools': allocation_pools})
     if not module.params['gateway_ip']:
         subnet.pop('gateway_ip')
+    if module.params['dns_nameservers']:
+        subnet['dns_nameservers'] = module.params['dns_nameservers'].split(',')
+    else:
+        subnet.pop('dns_nameservers')
     try:
         new_subnet = quantum.create_subnet(dict(subnet=subnet))
     except Exception, e:
@@ -247,6 +257,7 @@ def main():
             ip_version              = dict(default='4', choices=['4', '6']),
             enable_dhcp             = dict(default='true', choices=BOOLEANS),
             gateway_ip              = dict(default=None),
+            dns_nameservers         = dict(default=None),
             allocation_pool_start   = dict(default=None),
             allocation_pool_end     = dict(default=None),
         ),