Heartbeat frequently fails email test

[jMyles]

It looks like the string of failures from last night into this morning weren't errors - the emails were in fact late getting go gmail in each case. If they don't arrive in time to be read by the subsequent heartbeat, they don't work.

In the short term, in order to stem the noise of error messages, we need to somehow loosen the criteria. I.E., we don't need to get a call unless the email still hasn't arrived after two heartbeats. Or something.

[jMyles]

If we want to not be woken up every night, we need a fix. Who's on it? I vote for @rachelLagodka