[Wilds] Fix some minor classtree issues identified by unit tests

Summary: Ref T13098. I eventually got unit tests sort-of-almost running and they caught these two issues. Since the tests don't get very far with these classtree problems, just fix them up now so when `arc unit` actually runs later on it can meaningfully run tests.

Test Plan: Ran `arc unit`, after other changes let it run, and saw fewer "class doesn't implement every abstract method" issues.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13098

Differential Revision: https://secure.phabricator.com/D19708

src/config/option/ArcanistWildConfigOption.php

@@ -32,4 +32,8 @@ final class ArcanistWildConfigOption
     return $value;
   }
 
+  public function getStorageValueFromValue($value) {
+    return $value;
+  }
+
 }

src/config/source/ArcanistFileConfigurationSource.php

@@ -1,11 +1,10 @@
 <?php
 
 final class ArcanistFileConfigurationSource
-  extends ArcanistConfigurationSource {
+  extends ArcanistFilesystemConfigurationSource {
 
   public function getFileKindDisplayName() {
     return pht('Config File');
   }
 
-
 }