GPII-724: The onOffSwitch's aria role is now "checkbox".
Since we are backing up those on/off toggles with html checkbox inputs, it looks like screen readers can understand better their role if they are marked as checkboxes instead of buttons.
Merge pull request #62 from chrispetsos/GPII-724

GPII-724: Fixed problem with on/off switches always being reported as unselected from NVDA.