Fix bug related to img link for non-img files.

https://edx.lighthouseapp.com/projects/102637-studio/tickets/135-via-tender-studio-asset-locker-currently-returns-incorrect-xml-snippet

cms/static/js/base.js

@@ -498,7 +498,7 @@ function displayFinishedUpload(xhr) {
     }
 
     var resp = JSON.parse(xhr.responseText);
-    $('.upload-modal .embeddable-xml-input').val('<img src="' + xhr.getResponseHeader('asset_url') + '"/>');
+    $('.upload-modal .embeddable-xml-input').val(xhr.getResponseHeader('asset_url'));
     $('.upload-modal .embeddable').show();
     $('.upload-modal .file-name').hide();
     $('.upload-modal .progress-fill').html(resp.msg);

cms/templates/asset_index.html

@@ -28,7 +28,7 @@
         {{uploadDate}}
       </td>
       <td class="embed-col">
-        <input type="text" class="embeddable-xml-input" value='{{url}}'>
+        <input type="text" class="embeddable-xml-input" value='{{url}}' disabled>
       </td>
     </tr>
   </script>
@@ -69,7 +69,7 @@
                 ${asset['uploadDate']}
               </td>
               <td class="embed-col">
-                <input type="text" class="embeddable-xml-input" value='${asset['url']}'>
+                <input type="text" class="embeddable-xml-input" value="${asset['url']}" disabled>
               </td>
             </tr>
           % endfor
@@ -99,8 +99,8 @@
 				<div class="progress-fill"></div>
 			</div>
       <div class="embeddable">
-        <label>Embeddable XML:</label>
-        <input type="text" class="embeddable-xml-input" value='<img src=""/>'>
+        <label>URL:</label>
+        <input type="text" class="embeddable-xml-input" value='' disabled>
       </div>
 			<form class="file-chooser" action="${upload_asset_callback_url}"
                                 method="post" enctype="multipart/form-data">