Fix crash when DEBUG enabled

opening a conversation with "%" in subject would crash.

Change-Id: I7e9a901cbae986c574958d50cbc69dcfa3d29fd2
diff --git a/src/com/android/mail/ui/AbstractActivityController.java b/src/com/android/mail/ui/AbstractActivityController.java
index e83ba1d..329dbde 100644
--- a/src/com/android/mail/ui/AbstractActivityController.java
+++ b/src/com/android/mail/ui/AbstractActivityController.java
@@ -1835,8 +1835,7 @@
             Utils.sConvLoadTimer.start();
         }
 
-        MailLogService.log("AbstractActivityController", "showConversation(" + conversation + " )"
-                + "");
+        MailLogService.log("AbstractActivityController", "showConversation(%s)", conversation);
         // Set the current conversation just in case it wasn't already set.
         setCurrentConversation(conversation);
         // Add the folder that we were viewing to the recent folders list.