REST: Report state from PUT and DELETE

GET reports on|off, same behavior for PUT and DELETE.

Change-Id: I6fe0414a4ceba7c50a32790bca7ad77fd26f7842
diff --git a/src/main/java/com/googlesource/gerrit/plugins/readonly/ReadOnlyEndpoint.java b/src/main/java/com/googlesource/gerrit/plugins/readonly/ReadOnlyEndpoint.java
index caabb57..2482cab 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/readonly/ReadOnlyEndpoint.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/readonly/ReadOnlyEndpoint.java
@@ -58,7 +58,7 @@
     @Override
     public Response<String> apply(ConfigResource resource, Input input) throws IOException {
       state.setReadOnly(true);
-      return Response.ok("");
+      return Response.ok("on");
     }
   }
 
@@ -75,7 +75,7 @@
     @Override
     public Response<String> apply(ConfigResource resource, Input input) throws IOException {
       state.setReadOnly(false);
-      return Response.ok("");
+      return Response.ok("off");
     }
   }
 }