Improve mechanism of photo loading

[programmerr47]

As for now we load all photos by default urls, but in Flickr API there is a mechanism for choosing size of loading image. I need to provide an adapt existing function (provide a new class/service) for picking up correct server image. This will improve loading time.

[programmerr47]

I've added just an additional method.

In ideal we need to add special class, that will accept rect and Photo's instance and will generate output url on it.