Name message retrieval service thread

// FREEBIE

src/org/thoughtcrime/securesms/service/MessageRetrievalService.java

@@ -189,6 +189,7 @@ public class MessageRetrievalService extends Service implements InjectableType,
     private AtomicBoolean stopThread = new AtomicBoolean(false);
 
     MessageRetrievalThread() {
+      super("MessageRetrievalService");
       setUncaughtExceptionHandler(this);
     }