Use 1.7 Kick packets in InitialHandler where needed

1.7 clients that are kicked in the initial stage are sent packets with 1.6 kick body, causing strange client messages rather than the ban reasons I wanted it to display.

I've attempted to add a 1.7 disconnect method to initial handler that sends a 1.7 kick packet to the client in all the 1.7 sections of the code. I'm unsure if this was the correct way to fix this but it seems to be working for cancelled login events for me.