- Fix a few issues with BrowseDataSets.
  - Rename ParseDataSetUri to ParseUri
  - Add a static method CreateUri to format a dataset Uri from group, user, dataset name
    and object name
  - Automatically fill group="default" and user="<real_user>" when either of the two
    are not passed


git-svn-id: http://root.cern.ch/svn/root/trunk@23248 27541ba8-7e3a-0410-8455-c3a389f83636