Add a resource for updating configured Chef Server

[schisamo]

Since with_chef_server is a helper as opposed to resource, arguments passed to can only be evaluated in the compile phase. There are situations where the Chef Server ip/hostname won't be known until halfway through the CCR...for example you might be provisioning the new Chef Server at the beginning of the CCR. By adding a Chef resource that updates the Chef server config like with_chef_server we will get things like lazy attributes out of the box!

/cc @jkeiser @afiune

[jkeiser]

Not sure I'm on board with this exact proposal, but I totally agree with the need!