Messaging: Handle default SMS app setting properly

* We don't need two settings basically doing the same
* Handling the change needs to happen via RoleIntent, not
  ACTION_CHANGE_DEFAULT
* Our own name sometimes can't be retrieved from package manager (?) -
  just use it from strings

Change-Id: I28abc52329f00b33a316533f12a54a517cba3514

src/com/android/messaging/util/ChangeDefaultSmsAppHelper.java

@@ -32,7 +32,7 @@ public class ChangeDefaultSmsAppHelper {
     private Runnable mRunAfterMadeDefault;
     private ChangeSmsAppSettingRunnable mChangeSmsAppSettingRunnable;
 
-    private static final int REQUEST_SET_DEFAULT_SMS_APP = 1;
+    public static final int REQUEST_SET_DEFAULT_SMS_APP = 1;
 
     /**
      * When there's some condition that prevents an operation, such as sending a message,