Merge pull request #579 from MITx/sarina/fix_video_title

Fix display titles on video pages

lms/templates/video.html

-% if name is not UNDEFINED and name is not None:
-  <h1> ${display_name} </h1>
+% if display_name is not UNDEFINED and display_name is not None:
+  <h2> ${display_name} </h2>
 % endif
 
 <div id="video_${id}" class="video" data-streams="${streams}" data-caption-data-dir="${data_dir}">