Setup factory_girl
Initial ContentItem model.

Only has base_path field with validations.
Drop database before running tests in CI

Ensure's there's nothing left over from previous test runs (stale data, indexes and the like)
Minimal GET for content_items
404 for Mongoid DocumentNotFound errors
Add output fields to content_item
Exclude internal fields from JSON representation
Merge pull request #11 from alphagov/content_item_read

Read API for a content item.