We should rely on stable versions of squizlabs/php_codesniffer, aye?

Author: Ocramius

composer.json

@@ -20,7 +20,7 @@
     "require-dev": {
         "phpunit/phpunit": "^4.6 || ^5.2.10",
         "ocramius/proxy-manager": "^1.0 || ^2.0",
-        "squizlabs/php_codesniffer": "^2.0@dev",
+        "squizlabs/php_codesniffer": "^2.5.1",
         "phpbench/phpbench": "^0.10.0"
     },
     "suggest": {