Rename branded asset; moved to LMS as that's where it is referenced [OPEN-302]

lms/static/sass/multicourse/_edge.scss

@@ -175,7 +175,7 @@ $paleYellow: #fffcf1;
     width: 263px;
     height: 72px;
     margin: 150px auto 50px;
-    background: url(../images/edge-logo-large.png) no-repeat;
+    background: url(../images/edx-edge-logo-large.png) no-repeat;
     text-indent: -9999px;
     overflow: hidden;
   }