Update ecmaVersion to accept 2018/9 (#417)
Update ecmaVersion to accept 2018/9 (#417)

Per documentation:
>ecmaVersion - set to 3, 5 (default), 6, 7, 8, or 9 to specify the version of ECMAScript syntax you want to use. You can also set to 2015 (same as 6), 2016 (same as 7), 2017 (same as 8), or 2018 (same as 9) to use the year-based naming.
schemastore/schemastore,schemastore/schemastore