Nuance - conduit method to create items

Summary:
pretty simple. did the bare minimum in the editor, etc. to be able to create an item from the conduit console.

I put the work in the editor for initializing new values, rather than some initializeNewItem method, mainly because Items don't have policy directly but instead policy will be defined by the queue(s) the item is in. The editor is definitely going to host this work, so it felt like it might be better to do it this way in time...? anyway, easy to make an initializeNew method instead if you want to have that paradigm going all the time.

Test Plan: made an item from teh conduit console - success. verified errors for missing data as well

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D7879