Formatting breaks after most recent PHPCS update

[mousetraps]

Repro steps:

1. grab the latest source from master
2. run composer update to update dependencies
3. formatting operations fail with:

PHP Fatal error: main(): Failed opening required 'C:\src\php\php-language-server\src/../vendor/squizlabs/php_codesniffer/Config.php' (include_path='.;C:\php\pear') in C:\src\php\php-language-server\src\Formatter.php on line 6

The issue is also causing the travis build to fail. Working on a fix.