OPAL-1769: Setting currentTask to null when stopping a task. Adding a progressbar to the index administration list view
OPAL-1769: Trying a different approach for stopping...
Merge pull request #164 from emorency/master

OPAL-1769: Progress bar on administration view and setting the current task to null when stopping the indexation
OPAL-1769 ValuesReaderCallback implements isCancelled.