Essentials UI not scaled responsive when viewing on a telephone, meta-tag missing

When going to the Essentials page from a mobile device the mobile responsive design is not rendered properly. Check with jdegooijer and it seems a meta-tag is missing.

Steps to reproduce:
1) Create and start a project with Hippo Essentials
2) Open the Essentials app from a mobile device/telephone
Expected: Responsive design with the hamburger/hotdog menu
Actual: page rendered as large page