Fixed and enhanced Dependency Injection, Updated README

Hey,

I fixed the dependecy injection class, it did not inject anything caused by a missing method call (`resolve()`). Now the DI resolver also supports type hints, which will lead to a more strong typed code. In order to this, there is more autocompletion in IDEs like PHPStorm, cause they can't resolve the aliases which are configured the `app.php`.

The Application class is also updated, which now throws an exception when an alias could not be created.

I updated the readme to get the project up an running by simply copy and paste the terminal commands.

Greets, LinuxDoku