Update directory structure

Per zendframework/zend-expressive#176 (comment),
this patch does the following:

- Creates a `src/App/` subdirectory, and moves `src/Action/` and `src/Composer`
  beneath them.
- Creates a `test/AppTest/` subdirectory, and moves `test/Action/` beneath it.
- Updates the `autoload` and `autoload-dev` entries for `App` and `AppTest`,
  respectively, to reference the new paths.
- Updates the `App\Composer\OptionalPackages` class to reference
  `src/App/Action` instead of `src/Action/` when specifying the directory to
  remove during a minimal installation. It also ensures that the default tests
  are removed during minimal installation (which wasn't handled previously, and
  spotted when making the directory changes).

composer.json

@@ -29,12 +29,12 @@
     },
     "autoload": {
         "psr-4": {
-            "App\\": "src/"
+            "App\\": "src/App/"
         }
     },
     "autoload-dev": {
         "psr-4": {
-            "AppTest\\": "test/"
+            "AppTest\\": "test/AppTest/"
         }
     },
     "scripts": {

src/Composer/OptionalPackages.php → src/App/Composer/OptionalPackages.php

@@ -28,8 +28,8 @@
  * Add this script to composer.json:
  *
  *  "scripts": {
- *      "pre-update-cmd": "Zend\\Expressive\\Composer\\OptionalPackages::install",
- *      "pre-install-cmd": "Zend\\Expressive\\Composer\\OptionalPackages::install"
+ *      "pre-update-cmd": "App\\Composer\\OptionalPackages::install",
+ *      "pre-install-cmd": "App\\Composer\\OptionalPackages::install"
  *  },
  */
 class OptionalPackages
@@ -389,7 +389,10 @@ private static function requestMinimal(IOInterface $io)
     private static function removeDefaultMiddleware(IOInterface $io, $projectRoot)
     {
         $io->write("<info>Removing default middleware classes and factories</info>");
-        self::recursiveRmdir($projectRoot . '/src/Action');
+        self::recursiveRmdir($projectRoot . '/src/App/Action');
+
+        $io->write("<info>Removing default middleware class tests</info>");
+        self::recursiveRmdir($projectRoot . '/test/AppTest/Action');
 
         $io->write("<info>Removing assets</info>");
         unlink($projectRoot . '/public/favicon.ico');