At Weaveworks, we have a built a tool called Flux [1]. It is able to relate manifests in a git repo to images in container registry. It has a CLI client (for use in CI scripts or from developer's workstation), it also has an API server and an in-cluster component, as well as GUI (part of Weave Cloud [2]).
Flux is OSS [3], and we use it to deploy our commercial product, Weave Cloud, itself which runs on Kubernetes.