Method for terminating the proxy remotely

[amcintosh]

Hi. We've had an issue when using the es-proxy with cronjobs in kubernetes. The main container finishes its work and terminates, however the es-proxy sidecar continues to run and so the pod itself never finishes. We thus need to go manually clean these up periodically.

So, I'm hoping to add a patch for the proxy to accept a HTTP POST that gracefully exits, which our main container can invoke upon completion.