Add loading indicator

[darekkay]

When pressing "authorize & backup", this tool starts fetching all tasks and downloads them when finished. However, users don't know that this operation is in progress because there is no loading indicator. When clicking the direct link, it does work though (default browser loading icon).

Solution: Add either the default browser loading indicator or an on-page loading widget. This is especially important for #9

[fharper]

I came here to create this issue as I thought the tool wasn't working when I tried to export all. I tried with just uncompleted tasks, and saw it worked, so thanks for this tool.