Add version fields to more json metadata blobs

[danielgmyers]

• Add version field to partition metadata marker.
• Add version field to step input attribute map.

Note that since nothing about these json blobs is changing other than adding the new version field, nothing actually checks the new field when parsing the json. This will change in the future if/when we bump the version number.

https://github.com/danielgmyers/flux-swf-client/issues/119