Improved cert subject parsing

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1614065 13f79535-47bb-0310-9956-ffa450edef68
Catch and ignore NoSuchElementException when accessing CN attribute of a subject principal

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1614270 13f79535-47bb-0310-9956-ffa450edef68
Code clean; renamed some package private methods

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1614354 13f79535-47bb-0310-9956-ffa450edef68