Fix invalid JSON for W3TC S3 sample policy

s3-sample-policy.diff

Index: s3-sample-policy.txt
===================================================================
--- s3-sample-policy.txt	(revision 711148)
+++ s3-sample-policy.txt	(working copy)
@@ -15,9 +15,9 @@
         },
         {
             "Sid": "Stmt1339423675422",
-            "Action":s3:List*?,
+            "Action":"s3:List*?",
             "Effect":"Allow",
             "Resource":"*"
         }
     ]
-}
\ No newline at end of file
+}