string handling with += for new ruby version
string handling with += for new ruby version

spurti-chopra/travis-cookbooks,ljharb/travis-cookbooks,travis-ci/travis-cookbooks,spurti-chopra/travis-cookbooks,travis-ci/travis-cookbooks,spurti-chopra/travis-cookbooks,ljharb/travis-cookbooks,ljharb/travis-cookbooks,travis-ci/travis-cookbooks