* Fixed regression caused by transport refactoring
- Libuv should not close the socket until it has started it. Before this was enforced
by calling ReadStart before starting the frame but the flow has changed. Now that closing the connection
is communicated via the pipe, we need to start consuming writes after calling ReadStart.
- Renamed OnSocketClosed to Close and moved dispose and logging into that method.
Fixes#1571
- Replace endpoint configuration via .UseUrls() or --server.urls with Listen*
methods on KestrelSerrverOptions.
- Replace IConnectionFilter with IConnectionAdapter which no longer exposes
ServerAddress via a context.
- Simplify libuv Listener classes
- Support systemd socket activation
- Add docker-based test for systemd socket activation to be run on Travis