Disable JSON compression

[pdinklag]

Some webservers integrate automatic compression of JSON files. This breaks asynchronous downloads of json.gz files via AJAX, which the MinecraftStats client then cannot decompress. The reasons are not entirely clear to me, but this has been a problem in the past.

In any event, since server-side compression can apparently be considered standard functionality, this means that MinecraftStats should no longer do it and move that responsibility to the admin.