Motivation:

Uptime example is lack of server.
UptimeClient's code style is a little bit different from others, which make reader feel confused.
We don't need to create a new Bootstrap instance each time client reconnect to server.

Modification:

Add UptimeServer and UptimeServerHandler which simply accept all connection and discard all message.
Change UptimeClient's code style.
Share a single Bootstrap instance.

Result:

Uptime server support.
Consistent code style.
Single Bootstrap for all reconnection.