dev/core#2046 Migrate BAO_Address::create towards standardisation

dev/core#2046 Migrate BAO_Address::create towards standardisation

Our standard expectation is that each BAO will have a create action that handles a single entity. For legacy
reasons Address.create has special handling for multiple addresses. This extracts that handling
into a separate function (legacyCreate) and updates the (very few) places currently calling create to
call that.

With this merged apis v3 & v4 can call Address.create  - currently v3 is hard coded to call add and
v4 bypasses the BAO altogher. The v4 api bypass means we are not managing is_primay integrity on v4 api calls