Improved parameterized tests

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpasyncclient/trunk@1603109 13f79535-47bb-0310-9956-ffa450edef68
Moved embedded test server base class

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpasyncclient/trunk@1603190 13f79535-47bb-0310-9956-ffa450edef68