CHEF-4426 - knife cookbook upload doesn't work on windows when working with :versioned_cookbooks

This PR restores the using of symlinks while uploading multiple cookbooks with different versions and fixes the problem on windows. 

Tested locally on my windows VM and http://manhattan.ci.opscode.us/job/chef-cvt-test/50/

@danielsdeleo thoughts?
@lamont-granquist / @adamedx / @jkeiser FYI.