Radiator RSS

We added 3 new pingdom pings to pingdom:
 - Network Front Rss
 - Editors Picks Rss (Google News)
 - Sport Cycling Rss

This is to ensure there is visibility on the RSS feeds for when they break.

The endpoint `/radiator/pingdom` was not showing me any response, so I changed it to return `JSON` instead of a `String`, and stopped parsing in javascript.

@rich-nguyen @gklopper 
```return /elb|host|cdn|rss/.test(check.name.toLowerCase());```

might make more sense