Failed connect should not trigger onClose, should log failure reason if possible

[niloc132]

Presently, if the checksum check fails for whatever reason, the Server.onOpen call never is invoked, but Server.onClose is, which doesn't make sense. Instead, it should not be called at all.

Additionally, those various failed checks should call in to some common log API, if possible, or at least offer the chance for the Server implementation to handle it.