Remove fontello

This is no longer used now that the octicons include video/audio
on/off icons that are used in the collaboration package.

static/root-view.less

@@ -69,10 +69,3 @@ html, body {
     min-width: 0;
   }
 }
-
-@font-face {
-  font-family: 'fontello';
-  src: url("fontello.woff") format("woff");
-  font-weight: normal;
-  font-style: normal;
-}