Allow a couple of Composer plugins (#63)

Author: danielbachhuber

composer.json

@@ -24,7 +24,11 @@
             "php": "5.4"
         },
         "process-timeout": 7200,
-        "sort-packages": true
+        "sort-packages": true,
+        "allow-plugins": {
+            "dealerdirect/phpcodesniffer-composer-installer": true,
+            "johnpbloch/wordpress-core-installer": true
+        }
     },
     "scripts": {
       "lint": "run-linter-tests",