move download url and checksums to attribute file
move download url and checksums to attribute file

ClogenyTechnologies/powershell,cookbooks/oc-powershell,opscode-cookbooks/powershell,dpiessens/powershell,bheuvel/powershell,trevorghess/powershell,burnzy/powershell,Nordstrom/powershell,criteo-forks/powershell,chef-cookbooks/powershell