Enhancements for Uploads Repository API

[Piotr Jasiun]

Uploads Repository is missing some important methods:

• repository.isFinished - returns true if all uploads are done,
• repository.loaders - returns all loaders in upload repository.

It would be useful if one wants to block save button until all uploads are done.

[Jonathan]

This is a pretty important feature since large uploads may take a while.

[Piotr Jasiun]

Done. Changes in ​t/12965.

Changes:

• uploadRepository.loaders is now global; I can imagine some scenarios when user want to get all active uploads or all statuses; there is no reasone to keep it private;
• introduced uploadRepository.isFinished and loader.isFinished; these methods could be very useful if user want to prevent some actions until all uploads are done;
• removed uploadRepository.get; since loaders is global this method do nothing.

[Piotrek Koszuliński]

Merge to major with ​git:6fce1f8.