Add support to create annotations on the deployment and statefulsets

[clockworksoul]

This issue was identified as https://github.com/lalamove/helm-elasticsearch/issues/6. Many thanks to that team for pointing this out, and don't be shy, feel free to submit PR's on your fixes!

Currently, there's no way to push down annotations to the deployments/statefulsets, which would be useful to connect the Elasticsearch pods more permanently to the Prometheus Kubernetes autodiscovery plugin.