No need to restart Web-server now to see changes in dynamic UI.

Workflow is simpler now: edit form definition YAML-file, save it,
reload the form it affects. Voila!

Implements: feature MRN-1147
Cherry-picked from dc78dc3b68705b4f1826864067731d31d4d603b0

Change-Id: I72d68c17b829f9252560ecd01335656ffba0b262