Fix hijacking of Start New Course button in IE

The "Start New Course" button on the main dashboard was randomly bringing up the standard built-in Canvas form instead of redirecting to the SFU form. The right-hand sidebar gets loaded via ajax, and for some reason the event that I'm overriding wasn't present on the page at that time, only in IE. This fix checks for the presence of that object first, and if it isn't found, waits 100ms and tries again. Tested on IE 9 & 10, FF and Chrome. **Note**: this was already changed in-place on ap1..10; which is why I'm doing a pull request against sfu-deploy. Once merged I'll pull it into sfu-develop as well.