Heartbeats

[ablease]

@Zerpet I put in a basic graceful close mechanism for the Heartbeat done channel. I might still be susceptible to a race condition. The test passes without panicking at least!

I'll make another test case to call the locator operation for sending a heartbeat shortly (to pass the failing static check)

I had tried to incorporate the gleak leak detector. I see you tried as well, but I couldnt not get it to fail? Let me know what you think about having a gleak test.