add validate user's token method for v2 and bug fix for reauth
diff --git a/provider_client.go b/provider_client.go
index e813e0e..ef028cf 100644
--- a/provider_client.go
+++ b/provider_client.go
@@ -185,10 +185,21 @@
 
 	if resp.StatusCode == http.StatusUnauthorized {
 		if client.ReauthFunc != nil {
-			err = client.ReauthFunc()
+			// make sure ReauthFunc only exec one time, or will occur endless recursive loop when admin reauth fail
+			execFunc := client.ReauthFunc
+			client.ReauthFunc = nil
+			err = execFunc()
+			client.ReauthFunc = execFunc
 			if err != nil {
 				return nil, fmt.Errorf("Error trying to re-authenticate: %s", err)
 			}
+
+			if options.MoreHeaders != nil {
+				options.MoreHeaders["X-Auth-Token"] = client.TokenID
+			} else {
+				options.MoreHeaders = client.AuthenticatedHeaders()
+			}
+
 			if options.RawBody != nil {
 				options.RawBody.Seek(0, 0)
 			}