SLIDER-622 warn if the directory is still present after the delete (shutdown race condition problem on NTFS)
SLIDER-637 purge ZKInstance uses in the accumulo and hbase providers
Merge branch 'develop' into feature/SLIDER-622-windows
SLIDER-637 rm unneeded test in TestZKIntegration
SLIDER-622 spin for deletion
SLIDER-622 add spin-checks for cluster dir deletion...deals with NTFS problems