Use PSR-4 for all classes (#69)

Psr/Log/Test/DummyTest.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Psr\Log\Test;
+
+/**
+ * This class is internal and does not follow the BC promise.
+ *
+ * Do NOT use this class in any way.
+ *
+ * @internal
+ */
+class DummyTest
+{
+    public function __toString()
+    {
+        return 'DummyTest';
+    }
+}

Psr/Log/Test/LoggerInterfaceTest.php

@@ -136,11 +136,3 @@ public function testContextExceptionKeyCanBeExceptionOrOtherValues()
         $this->assertEquals($expected, $this->getLogs());
     }
 }
-
-class DummyTest
-{
-    public function __toString()
-    {
-        return 'DummyTest';
-    }
-}