Refactor AcmeService creation into Factory

src/AcmeFactory.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace Kelunik\AcmeClient;
+
+use Kelunik\Acme\AcmeClient;
+use Kelunik\Acme\AcmeService;
+use Kelunik\Acme\KeyPair;
+use Webmozart\Assert\Assert;
+
+class AcmeFactory {
+    public function build($directory, KeyPair $keyPair) {
+        Assert::string($directory);
+
+        return new AcmeService(new AcmeClient($directory, $keyPair));
+    }
+}