Use native kubernetes ways of configuration

I'm currently using the helm chart in the incubator (https://github.com/helm/charts/tree/master/incubator/vault), and trying to migrate over to this official chart.

Unfortunately a lot of what is done in this helm chart is so much harder that the one from the incubator. Annotations for the pod for example require you to use a string instead of helm parsing it, allowing for the same configuration one would do for kubernetes itself. Same goes for volume and mounts.

Compare the incubator Vault chart linked in the issue with the official chart's configuration and templates, focusing first on pod annotations, volumes, and mounts. Determine how the chart currently expects these values and how native Kubernetes-style structures are represented. Done means these settings can be configured without encoding them as strings, with the affected chart behavior verified.

Written by the indexing model from the issue text.