app /
- should not authorize without credentials
- should not authorize with bad credentials
- should authorize with good credentials

app /photos
- should not authorize with bad credentials
- should authorize with good credentials

app /photos/favorites
- should not authorize with bad credentials
- should authorize with good credentials

app /photos/collage
- should not authorize with bad credentials
- should authorize with good credentials

app /photos/favorites.json
- should be publicly available

flickr_user
- should be valid
- should require fa_id

photo
- should be valid
- should require flickr attributes
- should toggle favor
- should use favorites scope
- should construct_small_url on create
- should get_sizes when favored