Remove integer port requirement for Facebook

lib/Facebook.js

@@ -285,9 +285,6 @@ function Facebookbot(configuration) {
         if (!port) {
             throw new Error('Cannot start webserver without a port');
         }
-        if (isNaN(port)) {
-            throw new Error('Specified port is not a valid number');
-        }
 
         var static_dir =  __dirname + '/public';