Handle missing pipeline in merge request widget

Merged Winnie Hellmann requested to merge winh-mr-widget-no-pipeline into master

What does this MR do?

Display a message and spinner if pipeline for a merge request hasn't been created yet.

Screenshot

Screen_Shot_2017-06-22_at_10.16.36

What are the relevant issue numbers?

fixes #32987 (closed)

Edited by Winnie Hellmann