various improvements

Sorry, for the large PR, I had to do this for a project, and I figured you might just want to take it as it is.
Please apologize the stylistic changes, but I needed to support current chef best practices (rubocop and foodcritic).
I added chefspec to first make sure my changes did not alter existing behavior. All new features come with both chefspec and serverspec test, chefspec coverage is at 100%.

I added the version bump and documentation for 1.0.3, which I think you forgot to commit to github.

Notable new features:

* switched to berkshelf v3
* added chefspec tests
* added rubocop checks
* added foodcritic checks
* added travis-ci
* added serverspec tests
* clean up leftovers from old cookbook versions
* remove bzr directory (for vcs git)
* initialize etckeeper upon installation
* set email in git config via attribute