Found that the id from the ObjectAttribute dit not point to the id of th...

Found that the id from the ObjectAttribute dit not point to the id of the merge request. In my cases the iid has the number of the merge request.

This commit adds the iid to the ObjectAttribute and changes the GitLabMergerCause description to us this instead of the id.

The current implementation will show builds prior to this updates as #null as we don't have the correct data available  (GitLab Merge Request #null : testing => master)