Define cookbooks path and fix version of chef on leader.
Define cookbooks path and fix version of chef on leader.

Without defining cookbooks_path config chef reports the error.

412 Precondition Failed: No such cookbook: rails-sample

Also keeps the leader chef version the same as web-server's version.

GoogleCloudPlatform/scalable-resilient-web-app,GoogleCloudPlatform/scalable-resilient-web-app,GoogleCloudPlatform/scalable-resilient-web-app