Fix PV error during deployment

[arthurdm]

In recent minikube and ICP versions, we now get an error when deploying the chart:

Error: release vote failed: PersistentVolume "cloudant-pvc" is invalid: spec.capacity[storage]: Invalid value: "0": must be greater than zero

A temporary workaround has been committed via PR #1 , but that hardcoded value shouldn't be needed.