Migrate graceful shutdown into app framework

[alldroll]

From https://cloud.google.com/blog/products/gcp/kubernetes-best-practices-terminating-with-grace

It's important that an application handles termination gracefully so that there is minimal impact on the end-user and the time-to-recovery is as fast as possible! In practice, this means your application needs to handle the SIGTERM message and begin shutting down when it receives it. This means saving all data that needs to be saved, closing down network connections, finishing any work that is left, and other similar tasks

We have already implemented this feature here. It is time to migrate this feature into app framework in order to provide graceful shutdown for other services.