Use wkfs to manage the lets encrypt cache

README.md

cmd/cashierd/main.go

server/helpers/vault/vault.go

server/wkfs/vaultfs/vault.go

vendor/github.com/nsheridan/autocert-wkfs-cache/cache.go

vendor/github.com/nsheridan/wkfs/s3/s3.go

vendor/go4.org/wkfs/gcs/gcs.go

vendor/go4.org/wkfs/wkfs.go

vendor/vendor.json