StatusPage.io degraded performance reporting

[bergie]

In situations like the recent AWS outage the Heroku API may be down, affecting guv's ability to auto-scale our infrastructure.

2015-09-23T16:24:29.463496+00:00 app[guv.1]: ERROR: { [Error: Expected response to be successful, got 503]
2015-09-23T16:24:29.463501+00:00 app[guv.1]:   statusCode: 503,
2015-09-23T16:24:29.463503+00:00 app[guv.1]:   body: 
2015-09-23T16:24:29.463504+00:00 app[guv.1]:    { id: 'unavailable',
2015-09-23T16:24:29.463506+00:00 app[guv.1]:      message: ' Heroku has temporarily disabled this feature, please try again shortly. See https://status.heroku.com for current Heroku platform status. ' } }

Would be nice to report this as "degraded performance" to statuspage.io via their API:

http://doers.statuspage.io/api/v1/components/

Related to #5

[bergie]

Similarly, if guv can't talk to the message queue, we should report that as an outage