Reduced TCP packet fragmentation for blocking connection

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1458267 13f79535-47bb-0310-9956-ffa450edef68
Unit tests for default blocking connection implementations

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1458268 13f79535-47bb-0310-9956-ffa450edef68