Removes useless empty folders, adds README files with explanations in useful empty folders
This to facilitate the creation of Git repositories where empty folders needs a file in or must be ignored
Especially when you want to keep the OFBiz Subversion repository inside the Git repository (useful for committers)

git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1580865 13f79535-47bb-0310-9956-ffa450edef68