Auth: Add page to change password.

Configure launcher as a default return to address.

Use standard X-Forwarded-User instead of custom X-User header.
Add X-Forwarded-UserId header holding user unique identificator.

Change-Id: Ib2e6329ba9fb91d2cc9a86b0c5fc78898769e3b8
diff --git a/apps/url-shortener/main.go b/apps/url-shortener/main.go
index 23365fd..ff87094 100644
--- a/apps/url-shortener/main.go
+++ b/apps/url-shortener/main.go
@@ -163,7 +163,7 @@
 	if !*requireAuth {
 		return anyUser, nil
 	}
-	if user := r.Header.Get("X-User"); user != "" {
+	if user := r.Header.Get("X-Forwarded-User"); user != "" {
 		return user, nil
 	} else {
 		return "", fmt.Errorf("unauthenticated")