Remove underlines in related video links

Summary: Side effect of base styles changing to default text-decoration: underline, now we have to try if we don't want the underline

Test Plan:
Before: looked like the top link
After: looks like the bottom link
https://s3.amazonaws.com/uploads.hipchat.com/6574/17223/W7uzKZ3CN1htQXm/upload.png

Reviewers: alpert

Reviewed By: alpert

Differential Revision: http://phabricator.khanacademy.org/D5022

Author: marcia

related-videos.js

@@ -29,7 +29,7 @@ Exercises.RelatedVideos = {
                     .end();
 
                 var inlineLink = self.anchorElement(video)
-                    .addClass("related-video-inline");
+                    .addClass("related-video-inline no-underline");
 
                 $("<li>")
                     .append(inlineLink)