Add required PHP extensions as composer.json requirements

 composer.json

@@ -8,6 +8,9 @@
        "google/gtfs-realtime-bindings": "^0.0.2",
        "monolog/monolog": "^1.24",
        "twig/twig": "^2.0",
        "twig/extensions": "^1.5"
        "twig/extensions": "^1.5",
        "ext-ftp": "*",
        "ext-pdo": "*",
        "ext-pdo_sqlite": "*"
    }
}