GPII-1014: Replace the slider adjuster for cursor size with plus/minus text field adjuster

The bug report: http://issues.gpii.net/browse/GPII-1014

This pull request also upgraded the infusion library to be in sync with the latest master: https://github.com/fluid-project/infusion/
I don't think you need `$` here since we know it's a jQuery object we can just call attr directly. I wonder if we should use `fluid.allocateSimpleId`so that we can ensure that the element has an id.