[flickr] Implement support for skip and count
[flickr] Implement support for skip and count

As the API needs to specify elements/page (100 at most) and the page we want,
more research is needed to find an algorithm that minimizes the number of
flickr requests.

MikePetullo/grilo-plugins,GNOME/grilo-plugins,MikePetullo/grilo-plugins,jasuarez/grilo-plugins,MathieuDuponchelle/grilo-plugins,MathieuDuponchelle/grilo-plugins,grilofw/grilo-plugins,jasuarez/grilo-plugins,grilofw/grilo-plugins,kyoushuu/grilo-plugins,vrutkovs/grilo-plugins,MathieuDuponchelle/grilo-plugins,vrutkovs/grilo-plugins,MikePetullo/grilo-plugins,GNOME/grilo-plugins,MathieuDuponchelle/grilo-plugins,vrutkovs/grilo-plugins,kyoushuu/grilo-plugins,vrutkovs/grilo-plugins,kyoushuu/grilo-plugins