Add support for postSuffix

The postSuffix configuration is avaliable on the server section
of the boot.js file, and is used to remove the port suffix from
the application's URL.

The application's baseUrl and baseUrlSecure options will not have
the port included in the URL if the option is set to true (default).

In addition, URLs returned by app.url() will also have the port
suffix removed from the URLs.

For backwards compatibility with previous protos versions, if the
portSuffix option is not present on the boot.js file, it will
be assumed as enabled (the same is valid if it's set to undefined).