A Crow app defines an interface to allow the developer access to all the different parts of the framework, without having to manually deal with each one.<br><br>
An app allows access to the http server (for handling connections), router (for handling URLs and requests), Middlewares (for extending Crow), amoung many others.<br><br>
Crow has 2 different app types:
##SimpleApp
Has no middlewares.
##App<m1, m2, ...>
Has middlewares.
##Using the app
To use a Crow app, simply define `#!cpp crow::SimpleApp` or `#!cpp crow::App<m1, m2 ...>` if you're using middlewares.<br>
The methods of an app can be chained. That means that you can configure and run your app in the same code line.