WIP setting up paperclip and writing a few tests

Now with s3!
[#67041100 #67475832] Rename feed_items -> index

Also fixed some rubocop violations.
[#67041100] Test attaching an image to a feed item

Also includes fixing tests and the database cleaner
[#67041100] Finish testing paperclip images

Also includes:

- test for the most_recent scope
- updated_at now included in the feed item serializer
- since_field is now :updated_at
- possibly some other stuff
[#67041100] Rename image styles to canonical names
[#67041100] Minor tweak to the routes
Merge pull request #11 from cloudspace/67041100_add_images_to_feed_items

Add images to feed items, among other updates