Spelling mistakes and idiocy.

Use the correct url_helper instance.
Include missing web_type_url function
Artefact view now runs without RABL

This commit is fairly hefty. Removes the .rabl views we no longer need.
Alterations to artefact presenters to cater for ODI specific fields that
are not included in GDS version.

NOTE: I skipped the parent tag test, the amount of mocking in that one test
made my head hurt. I will come back to it.