show git-lfs push hook's progress bar?

[dmalan]

Right now, students will see "Submitting..." for quite a file if submitting a big file. Could reveal progress of git-push by unhiding its stdout, but then students will see all of its noise. Could alternatively override git-lfs pre-push hook by running git-push with --no-verify and calling git lfs pre-push origin or such ourselves, revealing only its stdout.