Adding codehttp://netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.css/code to the User-defined Resources in the App settings will result in this:
code<script type="text/javascript" src="http://netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.css"></script>/code
So it won't work... I know I can copy to a new CSS file, but it doesn't seem very convenient.