Add fix for PHPUnit running on PHP 5.5

Author: Xethron

Tests/bootstrap.php

@@ -2,6 +2,12 @@
 
 function loader($class)
 {
+    // Support for pre-PHP 5.6 versions
+    if ($class === 'PHPUnit\Framework\TestCase') {
+      class_alias('PHPUnit_Framework_TestCase', '\PHPUnit\Framework\TestCase');
+
+      return;
+    }
     $file = $class . '.php';
     if (file_exists($file)) {
         require $file;