[PSR4] Add NormalizeNamespaceByPSR4ComposerAutoloadRector

[TomasVotruba]

Changes namespaces based on composer.json:

{
    "autoload": {
-        "classmap": "src" 
+        "psr-4": {
+            "App\\": "src/"
+        }
    }
}

• src/SomeFile/File.php

-namespace Blabla;
+namespace App\SomeFile;

class File
{
}

[TomasVotruba]

Cover also https://github.com/Webhose/webhoseio-PHP/pull/3/files