Merge in latest knife-essentials 0.8.6: knife deps, multi-cookbook_path, integration tests, polish

- Support multiple cookbook_paths and allow chef_repo_path to be specified in a separate place for location of roles, data bags, etc.
- New "knife deps" command
- New options to apply commands to the local fs instead of remote (and vice versa)
- Full suite of integration tests that spin up a chef-zero server and run knife commands against it
- Windows support for backslashes and knife list
- Lots of output and error polish
- Many edge case fixes