Update ruby version in the docs, Dockerfile, and Vagrantfile
Following the changes in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22555, this will update ruby version in the docs, Dockerfile, and Vagrantfile.
Edited by George Tsiolis
Following the changes in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22555, this will update ruby version in the docs, Dockerfile, and Vagrantfile.