[FEATURE] Bugfixes and optimisations

- Changed Middleware to interface - as it's easier to inherit and use in
  other frameworks/projects.

- RouterController now loads method based on request-method.

- Changed references to old Middleware abstract class.

- Middleware must now be instance of IMiddleware instead of Middleware
  class.

src/Pecee/Http/Middleware/BaseCsrfVerifier.php

@@ -5,7 +5,7 @@ use Pecee\CsrfToken;
 use Pecee\Exception\TokenMismatchException;
 use Pecee\Http\Request;
 
-class BaseCsrfVerifier extends Middleware {
+class BaseCsrfVerifier implements IMiddleware {
 
     const POST_KEY = 'csrf-token';
     const HEADER_KEY = 'X-CSRF-TOKEN';