Added support for .ico files:

-/mar/ico/hoon
 * Utilizes similar structure to /mar/png/hoon, w/ changed mimetype
-/lib/server
 * Added ico-response, again similar to png w/ same caching
-/app/file-server
 * Added reference to ico-response:gen

i showed you my ico, plz respond

pkg/arvo/app/file-server.hoon

@@ -222,6 +222,7 @@
             [~ %js]    (js-response:gen file)
             [~ %css]   (css-response:gen file)
             [~ %png]   (png-response:gen file)
+            [~ %ico]   (ico-response:gen file)
           ::
               [~ %html]
             %.  file

pkg/arvo/lib/server.hoon

@@ -110,6 +110,11 @@
     |=  =octs
     ^-  simple-payload:http
     [[200 [['content-type' 'image/png'] max-1-wk ~]] `octs]
+  ::
+    ++  ico-response
+    |=  =octs
+    ^-  simple-payload:http
+    [[200 [['content-type' 'image/x-icon'] max-1-wk ~]] `octs]
   ::
   ++  woff2-response
     |=  =octs

pkg/arvo/mar/ico.hoon

@@ -0,0 +1,12 @@
+|_  dat=@
+++  grow
+  |%
+  ++  mime  [/image/x-icon (as-octs:mimes:html dat)]
+  --
+++  grab
+  |%
+  ++  mime  |=([p=mite q=octs] q.q)
+  ++  noun  @
+  --
+++  grad  %mime
+--