Remove Berksfile.lock from repo

[rjhornsby]

cookbooks/Berksfile.lock should probably be removed from the repo. Its existence is having the effect of pinning old versions of things like the Windows cookbook, which is/are not compatible with current chef clients (deprecated features, etc).

I'm not suggesting anything you don't already know, but if cookbook dependency versions need to be pinned, this should be done in either Berksfile or metadata.rb. Most likely Berksfile.lock was added to the repo by accident.

This should also resolve #90 and #99.