Adding a progress bar so the screen loader knows when folders are loadin...

...g, and making the file link more screen reader friendly

Before this pull request the screen reader does not get notified that anything is happening on the page, and the sighted user does not have much indication that things are happening as the busy cursor does not show over the table.

I am willing to hide the progress bar from the sighted user and I fully admit the progress calculation is a bit dumb, but it is better than nothing.