Update patient model parse handling of race and ethnicity

### Story ###
- https://www.pivotaltracker.com/story/show/79806350

### Notes ###
- ```race``` and ```ethnicity``` are extracted from the backend hash/object representation, which happens twice when loading the ```deepClone()```'d model in the patient builder
- Note: the desired race and ethnicity were always being saved correctly, but not rendered when editing the patient within the patient builder
I think we already have some decent workarounds in place (mapping from backend to client-side and vice versa), so I am hesitant to update the attribute entirely.

How about this as an alternative:
```
# extract demographics from hash, or use extracted values when cloning
attrs.ethnicity = attrs.ethnicity?.code || attrs.ethnicity
attrs.race = attrs.race?.code || attrs.race
```