Enable cli_spec examples under more rubies.

Some of them have been limited to ruby 2.0, but adding .to_a solves the problem.
Fix bug that causes unwanted reading of RuboCop's .rubocop.yml.

Other projects would get configuration meant exclusively for RuboCop itself if they didn't have their own .rubocop.yml.
Merge pull request #737 from jonas054/fix_config_loader

Fix config loader