Lightweight CI support for Git Repo

[tanmoysrt]

We will not support polling or cronjobs for checking updates. (Maybe later on a time we can)
We are delaying this method, as it can take significant resource to check git repo, image manifests.

Instead we will opt for webhook based updates -

1. If deployed from image, we will provide a webhook with unique token which can be configured in docker hub / other image repository
2. If deplotyed from git, we will provide a endpoint which can be updated in repository settings to trigger new build