add an icon for The Cloud

I am befuddled that Twitter Bootstrap has no built-in Icon for The Cloud,
and also that Chromium's depiction of CLOUD (U+2601) has an uncanny
resemblance to PILE OF POO (U+1F4A9) when rendered small, and looks like a
looming Frankenstorm when rendered large, and not a sweet, sunny, nothing
can go wrong The Cloud.
<http://www.fileformat.info/info/unicode/char/2601/browsertest.htm>

So, I must resort to irony in my choice of icons.

templates/sidebar/alert.hamlet

@@ -5,15 +5,15 @@
     $if block
       <h4 .alert-heading>
         $maybe i <- alertIcon alert
-          <i .icon-#{bootstrapIcon i}></i> #
+          #{htmlIcon i} #
         #{h}
     $else
       $maybe i <- alertIcon alert
-        <i .icon-#{bootstrapIcon i}></i> #
+        #{htmlIcon i} #
       <strong>#{h}</strong> #
   $nothing
     $maybe i <- alertIcon alert
-      <i .icon-#{bootstrapIcon i}></i> #
+      #{htmlIcon i} #
   #{renderAlertMessage alert}
   $maybe button <- alertButton alert
     <br>