Examples and clarifications for passing arguments to IoC constructors

From http://laravel.com/docs/4.2/ioc it is not clear how to pass arguments to the constructors in the IoC container.   This situation arises when a class needs not only a specific class as a dependency, but a specific instance of those classes.  It is not clear from the current documentation how to pass additional parameters to the constructor.

This pull request adds some examples for this scenario, clarifies the differences between `$this->app->bind` and `App::bind`, and improves formatting.