Rubocop testing of the attributes and testing documentation.

The Testing section of the README.md was broken out into the new TESTING.md to
explain how the cookbook is being tested. Rubocop is testing the attributes/
files and the .rubocop.yml has documented excluded rules.

Change-Id: I0a5f4124a061617779425490d198c00d931c4cc1
Merge "Rubocop testing of the attributes and testing documentation."