Fixed compile error from last commit (oops)

auth/user.go

@@ -28,5 +28,5 @@ func (user *User) LoggedOut() bool {
 
 // NewUser creates a new User object
 func NewUser(method Authenticator, id, level string, data map[string]string) *User {
-	return &User{id, level, data, method, false}
+	return &User{id, level, data, nil, method, false}
 }