os-tenant-networks

This commit adds support for the os-tenant-networks extension.
diff --git a/openstack/compute/v2/extensions/tenantnetworks/urls.go b/openstack/compute/v2/extensions/tenantnetworks/urls.go
new file mode 100644
index 0000000..2401a5d
--- /dev/null
+++ b/openstack/compute/v2/extensions/tenantnetworks/urls.go
@@ -0,0 +1,17 @@
+package tenantnetworks
+
+import "github.com/rackspace/gophercloud"
+
+const resourcePath = "os-tenant-networks"
+
+func resourceURL(c *gophercloud.ServiceClient) string {
+	return c.ServiceURL(resourcePath)
+}
+
+func listURL(c *gophercloud.ServiceClient) string {
+	return resourceURL(c)
+}
+
+func getURL(c *gophercloud.ServiceClient, id string) string {
+	return c.ServiceURL(resourcePath, id)
+}