Complete dependencies.io configuration

Continued from gitlab-org/distribution/team-tasks#194 (closed)

Complete configuration of dependencies.io configuration for the CNG image:

Software	File	Notes
ca-certificates	alpine-certificates/Dockerfile	This might be tricky. But we might consider tracking the alpine image itself. At the very least, it may make sense to just drop the version constraint.
cfssl	cfssl-self-sign/scripts/install_cfssl.sh	non-semantic version 1.2, based on installing vs building from source.
kubectl	gitlab-redis-ha/Dockerfile and kubectl/Dockerfile	v1.13.4 from kubernetes/kubernetes. If possible, we should consider installing kubectl from the kubectl image into the gitlab-redis-ha image

For the charts, we should configure the following software

Software	File	Notes
hyperkube image	charts/gitlab/charts/operator/values.yaml
minio	charts/minio/values.yaml	non-semantic versioning: RELEASE.2017-12-28T01-21-00Z
nginx-ingress-controller	charts/nginx/values.yaml	not-quite semantic versioning 0.20.0 is nginx-0.20.0
defaultbackend	charts/nginx/values.yaml	non-semantic versioning: 1.4
redis_exporter (Currently tagged latest)	charts/redis-ha/values.yaml && charts/redis/values.yaml	latest => 0.30.0
registry	charts/registry/values.yaml	2.7.1, tags in vX.Y.Z format