Release version 1.1.5
Run tests on Ruby 2.1 and not in Ruby 2.0
Merge pull request #24 from github/test_on_2.1

Run tests on Ruby 2.1 and not in Ruby 2.0
Merge branch 'master' into support_posix_groups

* master:
  Run tests on Ruby 2.1 and not in Ruby 2.0
  Release version 1.1.5