Add NewLoadBalancerV2

To create Octavia service client

Change-Id: I7e87bcca14037f67f054c923959e377677cb3965
Related-bug: PROD-24928 (PROD:24928)
diff --git a/openstack/client.go b/openstack/client.go
index 3db846e..84543da 100644
--- a/openstack/client.go
+++ b/openstack/client.go
@@ -352,3 +352,16 @@
 		Endpoint:     url,
 		ResourceBase: url + "v2/"}, nil
 }
+
+// NewLoadBalancerV2 creates a ServiceClient that may be used to access the v2
+// load balancer service.
+func NewLoadBalancerV2(client *gophercloud.ProviderClient, eo gophercloud.EndpointOpts) (*gophercloud.ServiceClient, error) {
+	eo.ApplyDefaults("load-balancer")
+	url, err := client.EndpointLocator(eo)
+	if err != nil {
+		return nil, err
+	}
+	return &gophercloud.ServiceClient{ProviderClient: client,
+		Endpoint:     url,
+		ResourceBase: url + "v2.0/"}, nil
+}