Rename config in proxy to prevent messup with shades.

Origin commit: https://github.com/SpigotMC/BungeeCord/commit/cc0d3a8e490b005a5b2e0c417dd6538029842175
Added async PreLoginEvent to change online mode per connection.

Signed-off-by: xxyy <devnull@nowak-at.net>
Adapt PreLoginEvent to protocol hack, Fixes #21