Allow further customisation of kick text during initial server connection.

If a user is kicked at present while they are not fully connected to an upstream bridge they will be kicked with a message "Kicked whilst connecting to <server>: <reason>".

While the current code allows us to change "Kicked whilst connect to " (by editing messages.properties) you can not remove the server name from the message. This quick patch allows full customisation of the kick prefix using the existing translation system.