Define Repisitory RawChanges RPC
This RPC can be called in CE and EE since https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/18238
Part of gitaly#1138 (closed)
This RPC can be called in CE and EE since https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/18238
Part of gitaly#1138 (closed)