Added twig to composer requirements
Added response class extended from Symfony's HttpFoundation\Response
Added a Filesystem\Path class for storing paths to application directories
Removed the Application constructor and added a boot() method to replace the functionality
Instantiate the Path class as part of Application::boot()
Renamed Application::register() to registerServices(), and add a new registerServiceProvider() method which can be passed a service provider class name to automatically instantiate and register with the container
Added an interface for service providers
Added a TemplateInterface and an implementation TwigTemplate
Registered the template service provider on startup
Added a HomeResponder with associated twig templates and tweaked HomeAction to use the responder
Added storage/cache to .gitignore
Fixed typo on README.md - ADR stands for Action Domain Responder, not Action Domain Response