Update attributes to be rubocop compliant

- Add rubocop.yml in attributes/
- Add attributes rubocop test to Strainerfile
- Update attributes to comply with rubocop

Change-Id: Id0ef1ac5387f8b2b0bdf2034c9318344053551bd
Addresses: blueprint rubocop-for-metering
Merge "Update attributes to be rubocop compliant"