Revise the Feed design/layout

[earvingemenez]

The current Feed design is quite confusing. It should be able to cater different types of feed/relationship and not just the author creating a book (user --> book relationship)

Feed items:

1. followed user created a book
2. followed user edited a book
3. followed user follows another user
4. followed user favorited a book
5. followed user commented on a feed