Added a scale option (defaults to 1.0), which is used as a multiplier to resize the spinner.
I saw a couple requests (#280, #195) for automatically resizing the spinner to fit the target element. This doesn't do that, but it was good enough for my use case and might be able to help those people out as well.
Seems to be working fine but I haven't been able to test it with all combinations of options.
Add scale option to enable resizing of spinner