make windows_task idempotent, fixes #267
make windows_task idempotent, fixes #267

juliandunn/windows,blairham/windows-cookbook,GannettDigital/chef-windows,protec-cookbooks/windows,shoekstra/chef-windows,criteo-forks/windows,ruicovelo/windows,chef-cookbooks/windows,urban-institute/windows,rlaveycal/windows,stuartpreston/windows,autoclone/windows,opscode-cookbooks/windows,daptiv/windows