Add composer phpcbf and allow wordpress-core-installer (#24)

Author: danielbachhuber

composer.json

@@ -21,7 +21,8 @@
         "process-timeout": 7200,
         "sort-packages": true,
         "allow-plugins": {
-            "dealerdirect/phpcodesniffer-composer-installer": true
+            "dealerdirect/phpcodesniffer-composer-installer": true,
+            "johnpbloch/wordpress-core-installer": true
         }
     },
     "extra": {
@@ -52,6 +53,7 @@
         "behat-rerun": "rerun-behat-tests",
         "lint": "run-linter-tests",
         "phpcs": "run-phpcs-tests",
+        "phpcbf": "run-phpcbf-cleanup",
         "phpunit": "run-php-unit-tests",
         "prepare-tests": "install-package-tests",
         "test": [