move rubocop.yml -> .rubocop.yml
update travis and Rakefile rubocop tasks
update .travis.yml
Merge pull request #153 from SUSE/review_140804_align_version_of_ruby_with_ibs_use_one_version_at_once

[Review] Request from 'vlewin' @ 'SUSE/connect/review_140804_align_version_of_ruby_with_ibs_use_one_version_at_once'