Removed unneeded polyfill from the master

Author: GrahamCampbell

composer.json

@@ -22,8 +22,6 @@
         "psr/log": "~1.0",
         "symfony/polyfill-intl-icu": "~1.0",
         "symfony/polyfill-mbstring": "~1.0",
-        "symfony/polyfill-php54": "~1.0",
-        "symfony/polyfill-php55": "~1.0",
         "symfony/polyfill-php56": "~1.0",
         "symfony/polyfill-php70": "~1.0",
         "symfony/polyfill-util": "~1.0"