Improve exception messages.

Author: jakzal

Tests/Fixtures/bad_format.yml

@@ -0,0 +1,3 @@
+blog_show:
+	path:     /blog/{slug}
+	defaults: { _controller: "MyBundle:Blog:show" }

Tests/Loader/YamlFileLoaderTest.php

@@ -51,7 +51,15 @@ public function testLoadThrowsExceptionWithInvalidFile($filePath)
 
     public function getPathsToInvalidFiles()
     {
-        return array(array('nonvalid.yml'), array('nonvalid2.yml'), array('incomplete.yml'), array('nonvalidkeys.yml'), array('nonesense_resource_plus_path.yml'), array('nonesense_type_without_resource.yml'));
+        return array(
+            array('nonvalid.yml'),
+            array('nonvalid2.yml'),
+            array('incomplete.yml'),
+            array('nonvalidkeys.yml'),
+            array('nonesense_resource_plus_path.yml'),
+            array('nonesense_type_without_resource.yml'),
+            array('bad_format.yml'),
+        );
     }
 
     public function testLoadSpecialRouteName()