The most likely end user operation (or at least a valid one) for base64
encoding would be to encode the user-data, but leave all other values
as plaintext.
In order to facilitate that, the user can simply add:
b64-user-data=true
to indicate that user-data is base64 encoded.
Other changes here are to change the cloud-config and metadata keynames
that are used.
base64_all = boolean(True)
base64_keys = [list, of, keys]
Fixed up tests to accomodate.
214dd2745f