Use ReflectionClass to determine Controller inheritance

Issue: If a class extends another class that extends Sober\Controller\Controller it would be excluded.

Author: fiskhandlarn

src/Loader.php

@@ -100,7 +100,7 @@ protected function setClassesToRun()
             }
 
             // Exclude non-Controller classes
-            if (!Utils::doesFileContain($filename, 'extends Controller')) {
+            if (!$reflection->isSubclassOf('Sober\Controller\Controller')) {
                 continue;
             }