Client connections are open for 30 seconds after being closed.

Using example Echo.Server (only change being the //pipeline.AddLast(new LoggingHandler("SRV-CONN")); commented out) and modified Echo.Client (in order to create more parallel connections and make the problem more visible).

Each client does one round trip and then it is 'done'. Creating 50 clients at a time and whole round takes (on my machine) about 5-6s, I see number of opened connections (netstat, system resource monitor in win10) to level out - at about 300. Using different variations of number of clients and round times shows that connections are left open for about 30s after being disposed.

[Echo.Client.zip](https://github.com/Azure/DotNetty/files/925763/Echo.Client.zip)