It's possible to merge a MR while checking for CI status

When we are checking for CI status we should not allow to merge a MR.

When the button is clicked the MR is merged. Tested in gitlab.com with this MR -> https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9122

We need to add tests to guarantee this does not happens again.

Design

always make button red, unless positive pipeline outcome