SLING-2985 : tooling : show content of .content.xml in project explorer
 - WIP/Work in progress : adding prototype of content[-package][.content.xml] browsing. 'mounts' the syncDir as a new toplevel node to a sling-faceted project and allows browsing through folders/.content.xml-content.

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1511345 13f79535-47bb-0310-9956-ffa450edef68