FileHandler now deals with objects implementing the InputStreamSupport interface correctly.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/configuration/trunk@1463672 13f79535-47bb-0310-9956-ffa450edef68
Changed test class: Only use methods from FileBased interface to load and save XMLConfiguration objects.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/configuration/trunk@1463673 13f79535-47bb-0310-9956-ffa450edef68