update form action (create-snapshot-download) /danger/snapshots.html

I've changed the approach to how users deal with downloading Snapshots. Instead
of re-implementing the functionality for downloading files in the /storage
section of the site, the user now prep's the Snapshots (zips them up) and moves
them to the /storage/media directory. From there, users can download the zipped
file  and I haven't had to re-implement or write additional code.

templates/danger/snapshots.html

@@ -38,7 +38,7 @@
     {% for item in snapshots %}
     <div class="be-section-entry">
         <form class="be-gui-form"
-              action="/danger/download-snapshot"
+              action="/danger/create-snapshot-download"
               method="post">
             <input required
                    type="hidden"
@@ -52,7 +52,7 @@
 		    title="Click this to download '{{item}}' Snapshot"
 		    type="submit">
 	        <img alt="Download Snapshot {{item}}"
-		     src="/images/icons/down-arrow.png">
+		     src="/images/icons/transfer.png">
 	    </button>
         </form>