Re-designed hostname verification API and rewritten implementation code

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1618698 13f79535-47bb-0310-9956-ffa450edef68
Improved compliance with RFC 2818: default hostname verifier to ignore the common name of the certificate subject if alternative subject names (dNSName or iPAddress) are present