[WEB-1608] Minecraft account with space in name

A player managed to log on a pure vanilla java server as "alex 99" and being disruptive. It was not possible to ban using the username because it has a space in violation of Mojang's account naming policies as per https://help.mojang.com/customer/en/portal/articles/928638-minecraft-usernames

Looking up the UUID on the Mojang API reveals that there is indeed a space in the username

Please look into this as other servers are being hit by this player and only ip-ban is able to contain them.