Fixed websocket send message for event with handlers

[Limraj]

To Reproduce

1. Login as admin;
2. Created Data Source(virtual, update:5s, enable) as ds_1;
3. Created Data Point(in ds_1, settable, binary, no change) as dp_1;
4. Created Event Detector(for dp_1, on change, Information) as ed_1;
5. Created Script(script:'return 1') as sc_1;
6. Created Event Handler(for ed_1, type: script(set active: sc_1));
7. Created Watch List (for ds_1 - dp_1);
8. Set new Value for dp_1;
9. In log warn: Could not write JSON: No serializer found for class com.serotonin.mango.rt.event.handlers.ScriptHandlerRT