Extracted upload tagParams and upload url functionality into their funct...

Hello, I've extracted upload tagParams and upload url functionality into their own functions, this will facilitate frameworks like Angular fetching the server-side params.

The reason for doing this is so I could make a server-side service like:

/cloudinary/requestUploadAuthorization

which returns the signed upload params and upload URL. Then the client side framework (Angular in this case) composes the correct <img> tag and handles all the JS processing.

An alternative would have been for the server-side service to return the fully formed <img> tag, but this seemed less clean in the context of Angular or another framework which composes its own HTML widgets.

In either case, this is a rather harmless change which makes it possible to independently test these portions of the code in the future.