Download progress will be constrained from 0% to 90%, and the final 10% is for the binary to start. There's not much else that happens on Windows during startup so those are the only events I added.

If the binary is already downloaded, the progress ring will animate smoothly from 0 to 90.

If the newer app is used with an older service, the ring will just show indeterminate progress like it used to do.

Closes#100