Add instructions for how to access file post-upload

lib/gollum/public/gollum/javascript/gollum.dialog.js

@@ -102,6 +102,10 @@
       html += '<input type=file name="' + name + '">';
       html += '</form>';
 
+      if( fieldAttributes.context ){
+        html += '<span class="context">' + fieldAttributes.context + '</span>';
+      }
+
       return html;
     },
 

lib/gollum/public/gollum/javascript/gollum.js

@@ -154,7 +154,8 @@ $(document).ready(function() {
         title: 'Upload File',
         fields: [
           {
-            type:   'file'
+            type:   'file',
+            context: 'Your uploaded file will be accessible at /uploads/[filename]'
           }
         ],
         OK: function( res ) {