As an editor I want to be able to edit values of datatype URL.

Problem:
So far we don't support URL values.

Screenshots/mockups:

BDD
GIVEN
AND
WHEN
AND
THEN
AND

Acceptance criteria:

• valid URL values can be entered and saved
• invalid URL values are rejected
• validation is done based on the same criteria the repo uses

Open questions:

• How do we do error handling?
  • Potential errors include: spam blacklist triggered, wrong format/protocol