Improve notification formatting

[sparr]

Two changes here. First, the % in the notification is padded to three characters with spaces, so that the progress bar doesn't move around at 0 vs ## vs 100%. Second, reimplemented the progress bar to fix a bug where 0% displayed with two characters instead of zero, getting rid of an eval in the process.

[hastinbe]

Thanks, I like the bash-only alternative

[sparr]

I thought you might, right after I'd already committed the version with sed, so I went back to fix it :)