makes ajustments to modals on page load

@symbolist : https://github.com/edx/edx-platform/commit/cfaf1275a7a7a960d61404fdc92129a9c19e6987 actually broke the functionality in https://github.com/edx/edx-platform/pull/1401. I fixed it by having the js related to leanModal load once the page loads.

@dianakhuang