Adding get extension operation
diff --git a/openstack/networking/v2/networks/urls.go b/openstack/networking/v2/networks/urls.go
index 3f49261..8d350b1 100644
--- a/openstack/networking/v2/networks/urls.go
+++ b/openstack/networking/v2/networks/urls.go
@@ -6,6 +6,8 @@
 	"github.com/rackspace/gophercloud"
 )
 
+const Version = "v2.0"
+
 func APIVersionsURL(c *gophercloud.ServiceClient) string {
 	return c.ServiceURL("")
 }
@@ -13,3 +15,7 @@
 func APIInfoURL(c *gophercloud.ServiceClient, version string) string {
 	return c.ServiceURL(strings.TrimRight(version, "/") + "/")
 }
+
+func ExtensionURL(c *gophercloud.ServiceClient, name string) string {
+	return c.ServiceURL(Version, "extensions", name)
+}