Update take_survey usage in the birth RSP.
It's neg_{1,2}, not -{1,2}.
Add the .no survey taker helper back.  #2744.

response_set_populators/birth_spec.rb uses this.
SurveyTaker doc fixes.  #2744.
Make SurveyCompletion handle three-arg case for SurveyTaker.  #2744.
Update child_and_adhoc_spec.rb.  #2744.