Configure product_details and add initial JSON files for it.
Fix bug 1080066: Add per-locale stewards and fix email field.

Adds a new model for tracking per-locale stewards for a given interest.

Removes the magic in CommaSeparatedEmailField that converts the value
to a list, as this was screwing up the text inputs in the admin.

Also uses a text input for the fields instead of a textarea.
Merge pull request #115 from Osmose/locale-stewards

Fix bug 1080066: Add per-locale stewards and fix email field.