(bug) gathering-heatbeat markers arrive at the client with an unsafe integer value for user_guid
gathering-heartbeat markers are received with unsafe integer values where guid entities are sent as strings
```json
{
"user_guid":994952798468575247,
"entity_type":"group",
"entity_guid":"997822291385520137",
"marker":"gathering-heartbeat",
"updated_timestamp":1563367071,
"disabled":false,
"read_timestamp":null
}
```
This gives unexpected results if the value is use in Javascript
issue