make require_login and require_role available in the load_app

It would be cool to be able to:

``` perl
load_app 'App::User', prefix => '/user', require_login
load_app 'App::Admin', prefix => '/admin', require_role Admin
```

And then also be able to use it in the loaded apps:

``` perl
package App::User
use Dancer ':syntax';

### you only get here if you are logged in, but the next action is only available if you are an Editor
get '/' => require_role Editor => sub {
return 'You are Editor :)';
};

true;
```

Just an Idea, have not seen any possibility to do that yet ... maybe I overlooked something?

Review the load_app, require_login, and require_role entry points and determine how authentication and authorization are currently applied. Define the behavior for passing require_login or require_role to load_app and for using require_role inside a loaded app. Done means both example usage patterns work with clear tests or documented acceptance criteria.

Written by the indexing model from the issue text.