Fix: using Composer to parse .json array was attempting to load unpri…

…vileged plugins

```
composer/installers contains a Composer plugin which is blocked by your allow-plugins config. You may add it to the list if you consider it safe.
You can run "composer config --no-plugins allow-plugins.composer/installers [true|false]" to enable it (true) or disable it explicitly and suppress this exception (false)
See https://getcomposer.org/allow-plugins%
```

src/Composer/ComposerPackage.php

@@ -83,7 +83,7 @@ public static function fromComposerJsonArray($jsonArray, array $overrideAutoload
     {
         $factory = new Factory();
         $io = new NullIO();
-        $composer = $factory->createComposer($io, $jsonArray);
+	    $composer = $factory->createComposer($io, $jsonArray, true);
 
         return new ComposerPackage($composer, $overrideAutoload);
     }