To master - User can delete a favorite from a playlist

[MackHalliday]

Issue Number: #30

Description of Behavior

User can delete a favorite from a playlist. PlaylistId and FavoriteId passed into DELETE request playlists/:id/favorites/:id. Matching playlist and favorite deleted in favorites_playlist joins table. Favorite is not deleted from favorites table, nor is playlist deleted from playlist table.

Pull request checklist

Please check if your PR fulfills the following requirements:

• [x] Tests are written
• [x] Test coverage acceptable
• [x] Sad paths accounted for
• [x] Tested in browser

Merge to

• [ ] Development branch
• [ ] Staging branch
• [x] Master

Additional Comments