Pinterest clone written for FreeCodeCamp (https://www.freecodecamp.com/djmot).
User Story: As an unauthenticated user, I can login with Twitter.
User Story: As an authenticated user, I can link to images.
User Story: As an authenticated user, I can delete images that I've linked to.
User Story: As an authenticated user, I can see a Pinterest-style wall of all the images I've linked to.
User Story: As an unauthenticated user, I can browse other users' walls of images.
User Story: As an authenticated user, if I upload an image that is broken, it will be replaced by a placeholder image. (can use jQuery broken image detection)