Use atromic reference for socket bound to the connection

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1590022 13f79535-47bb-0310-9956-ffa450edef68
Use abortive close (RST) for shutdown of blocking connections

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1590023 13f79535-47bb-0310-9956-ffa450edef68
Added SO_SNDBUF and SO_RCVBUF socket config parameters

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1590024 13f79535-47bb-0310-9956-ffa450edef68