ESP =? Extensible Service Proxy

[Jofre]

https://github.com/GoogleCloudPlatform/endpoints-samples/blob/master/gce/README.md#L28

I think there is some confusion here, as ESP usually refers to Extensible Service Proxy, and not "Endpoints Server Proxy" as suggested by the README. There are other instances using this naming.

Maybe we are areferring to different things, but if ESP means Extensible Service Proxy, we sould unify the naming conventions to avoid confusion.

[simonz130]

Thanks for the suggestion, Jofre. I'm closing it as it was addressed already.