Adding tags to Cloudinary direct uploads

Had to generate a new timestamp + signature for each cloudinaryimages field in the list and pass as form data on the file input.
This required exposing `cloudinary.uploader` in `locals.cloudinary` so each field could run `direct_upload()` again with the tags as one of the options - resulting in a new signature.
The default timestamp + signature used by `jquery.cloudinary.js`, defined in a `script` tag on the base template does not support tags as there could be more than one cloudinaryimages field per list.