Make STORAGE_KEY work when using CookieStorage
Make STORAGE_KEY work when using CookieStorage

Unfortunately PHP will convert **dot**s into underscore when parsing cookie names! So we have to remove dots in our `STORAKE_KEY`s so that is possible to use a CookieStorage.

[The full list of field-name characters that PHP converts to _](http://ca.php.net/manual/en/language.variables.external.php#81080)
[A random blog post](http://harrybailey.com/2009/04/dots-arent-allowed-in-php-cookie-names/)
Sylius/Currency