support api details in config file

[travisghansen]

I'm interested in allowing for FreeNAS api (host, protocol, username, password, etc) details to be stored in some sort of config file outside the cluster. Reasoning is we have a pretty open cluster(s) that I'd like to be able to deploy the storage class in, but not worry about cracking down on things too much. Idea would be:

1. run the provisioner on FreeNAS itself (or generally out of the cluster)
2. support secrets out of cluster by passing a --secrets-file flag or similar

Structure of the secrets file would be something like the following directly mirroring the secrets in cluster:

---
<storage-class-name>:
  protocol:
  host:
  port:
  username:
  password:
  allowInsecure:
---
<storage-class-name>:
  protocol:
  ...

Interested in feedback on the idea.

[travisghansen]

@nmaupu any thoughts?