Moved AuthenticationException to Rest module

module/Rest/src/Exception/AuthenticationException.php

@@ -0,0 +1,12 @@
+<?php
+namespace Shlinkio\Shlink\Rest\Exception;
+
+use Acelaya\UrlShortener\Exception\ExceptionInterface;
+
+class AuthenticationException extends \RuntimeException implements ExceptionInterface
+{
+    public static function fromCredentials($username, $password)
+    {
+        return new self(sprintf('Invalid credentials. Username -> "%s". Password -> "%s"', $username, $password));
+    }
+}