404 when you try to create a new group-milestone

Summary

When you try to create a new milestone for a group, you get a 404 on https://gitlab.com/GROUPNAME/milestones/new

Steps to reproduce

Try to open https://gitlab.com/GROUPNAME/milestones/new with a group, in which you are allowed to create milestones.

Expected behavior

The UI to create a new milestone across several projects of one group should appear.

Actual behavior

Response with 404.

Personal note

Thanks for all the great work! It's a pleasure to use gitlab!