Don't require coveralls.gem outside CI
Don't require coveralls.gem outside CI

ENV['CI'] is travis' default environment vairable, which coderwalls.gem also sees.
http://docs.travis-ci.com/user/environment-variables/#Default-Environment-Variables
https://github.com/lemurheavy/coveralls-ruby/blob/87bde674f36ed4b590fd846be8370b9642b636fd/lib/coveralls.rb#L94

treasure-data/perfectqueue