[Bug] Hard-coded view file extensions take precedence over self-added, more accurately matching extensions.

The `Environment::getExtension($path)` method has a strong bias towards the two hard-coded extensions. In fact, the way the above method resolves the "correct" extension makes it impossible for me to associate view file extensions ending in `php` with a third party engine like Twig, Smarty etc.

Quick example:

    // Suppose we have a view file named `hello.twig.php` under our main
    // views directory that's ment to be consumed by the Twig templating
    // engine. Further suppose we properly added the engine by means
    // of a EngineServiceProvider and set it up correctly.

    $env->addExtension('twig.php', 'twig');

    // Current status of Environment::$extensions
    dump($env): {
        protected $extensions =>
        array(3) {
            'blade.php' => string(5) "blade"
            'php' => string(3) "php"
            'tiwg.php' => string(4) "twig"
        }
    }

    // The call to Environment::getEngineFromPath('home.twig.php') wrongly
    // returns the `php` engine instead
    $env->make('home', $data);

With the fix itself I've included a test in `ViewEnvironmentTest.php` that proofs the issue.