Endless loop when client terminates the connection

[folbricht]

When a client (properly) closes the connection, the server will take 100% CPU spinning in an endless loop. That's because in this case EOF is read which should cause the server to stop listening (break) but instead it goes back to listening (continue) and does that in a tight loop.

I believe https://github.com/goftp/server/blob/master/conn.go#L67 should be break instead of continue

[folbricht]

Added #8