Update berkshelf to 5.2.0
Update berkshelf to 5.2.0

This brings in the following fix which will allow ChefDK to build again:
https://github.com/berkshelf/berkshelf/pull/1623

Signed-off-by: Seth Chisamore <215bfe682a8577a270cfd5ba940454500e137d63@chef.io>

vinyar/chef-dk,chef/chef-dk,vinyar/chef-dk,chef/chef-dk,chef/chef-dk,vinyar/chef-dk