Profile now contains taxonomy field which can be any number of fixed categories
set across all items on import. This includes item type.

This was causing test failures - not sure about actual database

This matches the field name and simplifies the code somewhat

There are two new item types 'question' and 'rumor'.
Item types for GeoPoll data are 'question'.
Item types for RapidPro data are 'rumor'

remove unused import and fix pep8 white space

https://trello.com/c/Q9hEiE20/83-change-categories-available-to-match-those-specified-in-the-story

I think the version of the models you get for migrations doesn't include
the methods we defined, so the save method doesn't set slug
from name. So I have added explicit name and made the old
name, which was in slug format, into the value of slug.