A quick spike for the heartbeats

[andreasohlund]

Spike for #12

Shows how to get the endpoint SLA and react to it on the ServiceControl side.

See //todo:'s for discussion points

[andreasohlund]

Merged to develop

[dannycohen]

@andreasohlund - Can you elaborate a bit on our heartbeat extensibility story ? (i.e. how can a user add custom code to extend the heartbeat checks ? what are the required steps ?)

[andreasohlund]

The user would implement a heartbeat provider:

https://github.com/Particular/ServiceControl/blob/develop/Src/ServiceControl.EndpointPlugin/Operations/Heartbeats/HeartbeatInfoProvider.cs

and just add data to the heartbeat when the "HeartbeatExecute" method is called

[andreasohlund]

Like this:

https://github.com/Particular/ServiceControl/blob/develop/Src/ServiceControl.EndpointPlugin/BusinessMonitoring/EndpointSLAHeartbeatProvider.cs