Cookbooks Search

:fork_and_knife: :meat_on_bone: :pizza: :hamburger: :ramen: This implements the basic structure for both the [cookbooks directory](https://projects.invisionapp.com/d/main#/console/668453/16696873/preview) and the [cookbooks feed](https://projects.invisionapp.com/d/main#/console/668453/16704044/preview) which can be drilled in on by category, sorted by most recently updated or added, and searched upon using Postgres full text search. Basic pagination is also implemented here using kaminari.