First pass at a new artefact edit page

This splits the artefact form into two halves, using multiple wells to 
split up sections of the form instead of one large well.

Tabs have been removed, replaced with buttons to view history or archive 
the artefact: currently stubs to be implemented in a later commit.

I've removed the Name, Slug and Description fields for existing artefacts, 
as they would be disabled by default anyway. Unfortunately this breaks 
a few tests, so I've fixed some of them here.