Whitelist mode?

Could it be possible to implement a whitelist mode where the plugin only allows country codes set by an admin, but kick/block country codes not listed inside the whitelist file?

Taking a look at the code, it looks rather simple to implement the feature so I might push a PR.

[EncryptSL]

In next release i add whitelist mode for country and ip whitelist able to connect to join server when country is blocked.