Deprecate proxy-query `zerovm_sysimage_devices` config param

The `object-query` and `proxy-query` configurations both have a `zerovm_sysimage_devices` parameter. However, they are treated differently. (But the docs indicated that they are the same!)

- `object-query` requires a list of `image-name` and `path-to-file` values
- `proxy-query` requires a list of `image-name` values
  - We only have `image-name` parameters here, because the actual image files are not installed on the proxy nodes (they are only installed on the object nodes)

Clearly these are different things. So in the proxy configuration, this parameter has been renamed to the more accurate `zerovm_sysimage_device_names`.

This patch fixes all of that, including vagrant scripts and docs.

Let me know if I missed something.