Semantic Endpoint Versioning w/ App Update

[flandia]

It currently lacks a mechanism to actively inform users that their app is outdated. We will introduce a new mechanism in this project to

1. Check the earliest supported semantic versioning endpoint number, e.g., v4.
2. For all semantic versioning endpoint number less than that number, access to them result in 410 Gone.
3. Make a convention that if app receives 410 Gone, popup to notify user that their current app is outdated to use the current feature. They can choose to update or not to update based on their willingness.