more error types; RequestOptsBuilder error fixes
diff --git a/openstack/identity/v3/tokens/requests.go b/openstack/identity/v3/tokens/requests.go
index 39dede0..4b87311 100644
--- a/openstack/identity/v3/tokens/requests.go
+++ b/openstack/identity/v3/tokens/requests.go
@@ -260,7 +260,7 @@
 
 // Validate determines if a specified token is valid or not.
 func Validate(c *gophercloud.ServiceClient, token string) (bool, error) {
-	response, err := c.Request("HEAD", tokenURL(c), gophercloud.RequestOpts{
+	response, err := c.Request("HEAD", tokenURL(c), &gophercloud.RequestOpts{
 		MoreHeaders: subjectTokenHeaders(c, token),
 		OkCodes:     []int{204, 404},
 	})