Enforce "en" lang in tests.

Some tests compare the result to english strings.

Do not test UnixCommandExecutor on Windows.

PharTest: explain why PHAR writing test are skipped.

InstallCommandTest: mock checkRequirements to allow the tests to run.

Run php_parallel_lint before all other tests.

Close #846

Tests/PHPCI/Plugin/Util/Fake/ExamplePluginWithSingleRequiredArg.php

@@ -0,0 +1,29 @@
+<?php
+
+/**
+ * PHPCI - Continuous Integration for PHP
+ *
+ * @copyright    Copyright 2015, Block 8 Limited.
+ * @license      https://github.com/Block8/PHPCI/blob/master/LICENSE.md
+ * @link         https://www.phptesting.org/
+ */
+
+namespace Tests\PHPCI\Plugin\Util\Fake;
+
+use PHPCI\Plugin;
+
+class ExamplePluginWithSingleRequiredArg implements Plugin
+{
+
+    public $RequiredArgument;
+
+    function __construct($requiredArgument)
+    {
+        $this->RequiredArgument = $requiredArgument;
+    }
+
+    public function execute()
+    {
+
+    }
+}