Add progress indicator during driver installation

[audreytoskin]

When you click on the Install Drivers button, the bottom of the window says "Now installing drivers. This may take a while..." But there's nothing about what stage of the process it's at, or how much longer it might take, or if it's perhaps just stuck and needs to be restarted.

For long-running processes like this, a progress bar would be nice. Bonus points if it also adds a little more information about what's going on, such as "Part 1: Downloading..." and "Part 2: Installing...", or similar :)