404 status should raise 404 error, even if JSON is valid.
Mismatch between response status and JSON code raises an exception
photos.update/update now also accept a list of Photo objects
Delete methods should raise exception on failure, rather than returning False
After deleting an object's fields, name and id should be set to None
Replace_encoded parameter should be called photo_file, not encoded_photo
Status code mismatches are actually quite common.

Rather than raise an exception, just ensure we return the JSON code.
Don't test the tag/create endpoint, as it is redundant and will be removed.

See #38 for details.
Ensure album cover is updated to a Photo object during Album() initialisation
Remove invalid comment
object.add/remove_photos should accept photos list as first parameter

(even though it's not implemented yet)
Fix a couple of unit tests
Merge branch 'consistency_fixes' into development