Merge latest `master` into `integrate_with_strong_params` branch to

1. resolve (automatic) merge conflicts
2. make all tests pass. The problem only existed in this branch and was fixed by @rafaelfranca in commit [57fa9b40](https://github.com/rails/protected_attributes/commit/57fa9b40b71166b1f73dc0ed4ffb01409994c889)

With that all tests should pass and thus the branch should be ready for merging into master for the next release.