Add du_id and hh_id to instrument enumerator #4121
Remove debugging code. #4121
Use household person links to find household unit. #4121
Fix order by rank method. #4121
Add method to sort dwelling household links by rank. #4121
Enable household unit id example.

This required switching the survey that populates the pre_preg to spec_blood table because spec_blood has an hh_id property.
Simplify ordering code slightly. #4121
Methods no longer used. #4121
DRY up code dealing with COMMUNICATION_RANK_CL1. #4121
Expect situation when rank doesn't exist. #4121
Switching to mdes ordering. #4121

The codes seems intentionally ordered, so even though I don't agree with the ordering I will use the order the MDES prescribes.
Merge pull request #186 from NUBIC/4121-add_du_hh_to_enumerator

Add household and dwelling unit identifier to instrument enumerator