We don't need Ci::Project anymore

For commit status API we need Ci::Commit to reference GitLab project instead of CI project. That makes no sense to keep Ci::Project model.

I and @ayufan have a call and we decided to get rid of Ci::Project model. @ayufan will propose a plan of migration. Part of #2594 (closed) and Commit Status API issue

Part of this is done in !1455 (merged)

This seems to be a duplicate of https://gitlab.com/gitlab-org/gitlab-ce/issues/3474 now.

Added ~19173 label

Status changed to closed

Since we have Ci::Project merged into Project and it is in fact a duplicate, we can close this issue.