Moving the `namespaceToPath()` method to the Inflector
New AbstractController class for having a basic
implementation of the ControllerInterface
New app-wide and default exception handlers
Also, finally have the `run()` method to actually start the application
New method in the Router to setup the default error
routes in Klein for HTTP 40x errors
Now setting up our default error routes when
"preparing" the app
Finally implementing the `initializeController()`
method for creating controllers based off of a given URL namespace
Now attempting to use a controller's exception
handler to handle any exceptions in the controller callback execution