Fix. Rename module name from `Rubocop' to `RuboCop' as per the upstream change.

This concerns the following commit:

  https://github.com/bbatsov/rubocop/commit/ff167d8f202baf7a68955db0aaf0dc29afb7e7ee

Signed-off-by: Krzysztof Wilczynski <krzysztof.wilczynski@linux.com>
Add unit tests.

Signed-off-by: Krzysztof Wilczynski <krzysztof.wilczynski@linux.com>