Show All Pipelines for Merge Requests from All merge_request_diffs

Dimitryi added Merge Request Versions: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5467

We added Pipelines for merge request which shows Pipelines only for latest version: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5485

We should verify and extend our implementation to show all past versions.