interfaces: Renamed 'service DIRService' to 'service DirectoryService' in...

interfaces: Renamed 'service DIRService' to 'service DirectoryService' in order to prevent a class name clash when compiling XtreemFS under Windows. The problem occurred because file names under Windows are not case-sensitive, and the Java compiler generated class files in the same package for both the service type 'DIRService' and a mesasge type named 'DirService'.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@2893 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534