Fix syntax of IE 8 comment in example, which was being rendered on the page in some versions of FF for Mac OS X
Fix #108 - fix Firefox bug by focusing on "Next" button, so that hitting Enter moves you to the next step
Prevent IE from skipping steps on hitting Enter by preventing default behavior, which activates the "next" button a second time
Add CSS fallback properties and remove introjs-ie.css file
Better prevent default on IE8 and 9.
Also disable when focused