Added edX logo to announecment

templates/mitx_global.html

@@ -35,6 +35,7 @@
   <section class="course">
     <div class="announcement">
       <h1> Announcement </h1>
+<img src="/static/images/marketing/edx-logo.png" alt="" />
       <p>
       On May 2, it was announced that Harvard University will join MIT as a partner in edX.  MITx, which offers online versions of MIT courses, will be a core offering of edX, as will Harvardx, a set of course offerings from Harvard.
       </p>