Implement Hosted Chef / Private Chef Clients Endpoint in Erlang 

On the Erchef side, we do some post-processing of clients after they
are created to ensure they have the correct permissions, group
memberships, etc.  This doesn't	happen in Open Source Chef
(obviously), but due to the way code is both shared and altered at
compile time, we need to introduce a "hook" for this functionality
into `chef_wm`.