Jsonref

- Fix issue with proxies=False where it would not recurse through references to remove the proxies. 48

- `replace_refs` is now a function rather than a class method of `JsonRef` (The class method is still around, but deprecated.)
- New options were also added to `replace_refs`
- `jsonloader` is now a plan function rather than an instance of a class. (This is a breaking change if you were subclassing `JsonLoader`)

See notes in 43 for more details