Migrated integration tests to HttpServer from HttpCore 4.4

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1603443 13f79535-47bb-0310-9956-ffa450edef68
Added static method to close idle connections used by the fluent executor

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1603444 13f79535-47bb-0310-9956-ffa450edef68