Enhanced SSLContextBuilder and overloaded methods to load material

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1631692 13f79535-47bb-0310-9956-ffa450edef68
Improved SSL context setup tests

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1631693 13f79535-47bb-0310-9956-ffa450edef68
Cleaned up test SSL code

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk@1631694 13f79535-47bb-0310-9956-ffa450edef68