Upgrade spin.js to verion 2.0.1 and add support for it

With spin.js version 2.0, Ladda button's layout breaks. There was a change in options.top and options.left in spin.js and left:auto, right:auto does not work as before.

So, I modified options in createSpinner function in ladda.js to work with spin.js version 2. Please review this patch.