- Avoid multiple calls to `validates` for the avatar attributes.
- In a cropping process, don't check if the model inherits `User`, check if it responds to `:avatar_crop_size`.
This commit moves the note folder from
/public/uploads/note
to
/uploads/note
and changes the uploader accordingly.
Now it's no longer possible to avoid the access control by modifing the url.
The Avatar upload has been refactored to use an own uploader as well
to cleanly seperate the two upload types.
