Update Ruby version to 2.2.4 (latest previous stable) and update docs
Tests and issues added to https://github.com/gitlabhq/gitlabhq/issues/8696 were all fine after the upgrade.
Main issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/3340
Tests and issues added to https://github.com/gitlabhq/gitlabhq/issues/8696 were all fine after the upgrade.
Main issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/3340