function cybmeta_dequeue_fontawsome() {

    global $wp_styles;
    // we use preg_match to find only the following patterns as exact matches, to prevent other stylesheets that contain font-awesome expression to be also dequeued
    $patterns = array(
        'font-awesome.css',
        'font-awesome.min.css'
        );

    $regex = '/(' .implode('|', $patterns) .')/i';

    foreach( $wp_styles -> registered as $registered ) {

        if( preg_match( $regex, $registered->src) ) {
            wp_dequeue_style( $registered->handle );
            // FA was dequeued, so here we need to enqueue it again from the location we want (cdn in our code)
            wp_enqueue_style( 'font-awesome', '//netdna.bootstrapcdn.com/font-awesome/4.1.0/css/font-awesome.min.css' );
        }
    }

}
add_action( 'wp_enqueue_scripts', 'cybmeta_dequeue_fontawsome' );