Remove more code related to unused download button

More stuff that goes with 1aecb45.

Author: carols10cents

app/templates/crate/version.hbs

@@ -40,9 +40,6 @@
     </div>
 </div>
 
-{{! This is used to set the url of to actually download a file }}
-<iframe id='download-frame' style='display:none'></iframe>
-
 {{#if currentVersion.yanked}}
     <div class='crate-info'>
         <div>