Update deps and bump phpunit version

Author: AydinHassan

composer.json

@@ -34,7 +34,7 @@
     },
     "require-dev": {
         "composer/composer": "^1.0-alpha",
-        "phpunit/phpunit": "^5.4",
+        "phpunit/phpunit": "^5.6",
         "squizlabs/php_codesniffer": "^2.4"
     },
     "autoload" : {