Update spec to be rubocop compliant

- Add rubocop.yml in spec/
- Add spec rubocop tests in Strainerfile
- Update spec files to comply with rubocop

Change-Id: Ia1aabed7ab1ed21913e4783eec711c09777c9754
Addresses: blueprint rubocop-for-ops-messaging
Merge "Update spec to be rubocop compliant"