Issue #2247287 by donquixote: Drop automatic PSR-0 support for modules.

core/includes/bootstrap.inc

core/lib/Drupal/Core/DrupalKernel.php

core/modules/simpletest/simpletest.module

...rc/Tests/Plugin/Discovery/AnnotatedClassDiscoveryTest.php

...s/Plugin/Discovery/CustomAnnotationClassDiscoveryTest.php

.../Discovery/CustomDirectoryAnnotatedClassDiscoveryTest.php

...dules/plugin_test/src/Plugin/plugin_test/fruit/README.txt

core/phpunit.xml.dist

...tests/Drupal/Tests/Core/Field/FieldDefinitionTestBase.php

...sts/Drupal/Tests/Core/Plugin/DefaultPluginManagerTest.php

core/tests/bootstrap.php