Convert file tests to PSR-0

The file entity patch is now commited, yay!

#3: 1594254-file-tests-psr0-3.patch queued for re-testing.

Looks great! One question though.....

+++ b/core/modules/file/lib/Drupal/file/Tests/FileFieldTestBase.phpundefined
@@ -0,0 +1,228 @@
+/**
+ * @file
+ * Definition of Drupal\file\Tests\FileFieldTestBase.
+ */
+
+namespace Drupal\file\Tests;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Provides methods specifically for testing File module's field handling.
+ */
+class FileFieldTestBase extends WebTestBase {

Should FileFieldTestBase be an abstract class? I see some assertions in it, but does it make sense for a TestBase class to have assertions? If we want SimpleTest to avoid testing this TestBase, then we'd want to make it abstract.

I could be wrong here though, as I'm not perforectly familiar with the file field tests.

It wasn't an abstract class before, so I see no need :-) . RTBC!

This rebase work?

Committed and pushed to 8.x. Thanks!