Composer: Remove script and call PHPCS directly

Has the advantages of:
 - working on Windows machines.
 - extra CLI args such as `--sniffs` can be passed when calling `composer cs`.

Author: GaryJones

bin/phpcs

@@ -40,7 +40,7 @@
 			"bin/php-lint",
 			"bin/xml-lint"
 		],
-		"cs": "bin/phpcs",
+		"cs": "@php ./vendor/squizlabs/php_codesniffer/bin/phpcs",
 		"test": "bin/unit-tests",
 		"test-coverage": "bin/unit-tests-coverage",
 		"feature-completeness": [