UI Updates

In favor of a less confusing approach to branches, I closed #274 and #283 for this PR that contains the commits from both of them. This PR changes the app header, cookbook search result and search bar UI. It is being worked on by @danvolkens and myself.

Related Trello cards:

- platform helper - https://trello.com/c/qTlydvgj
- cookbook search result ui - https://trello.com/c/JLSmCuuh
- cookbook directory & search bar ui - https://trello.com/c/BEl1jGlB