make the spinner animation default to border

[factoidforrest]

There's no good reason to always type out the animation for the spinner. There are only two choices, and the "border" option is the obvious choice as a default.

This should be a non-breaking change.

[factoidforrest]

Im happy to add tests, just want to see if the core change here would be acceptable.

[kyletsang]

Sounds like a good idea. For your code, you could add a default parameter to animation and keep the existing bsPrefix bit the same.

[factoidforrest]

@kyletsang you're right, that's cleaner, I changed it. How does that look?

[kyletsang]

Thanks!