bv assignment: modify User#adapt_bv_to_postal_address to assign philistres without postal address to BV 00.
Task: List all addresses that could not be assigned to a BV.

These addresses have to be mapped using the task 'rake
import:bvs:additional_mappings‘.
bv assignment: adding task to fix assign philister users to bvs if they are not assigned, yet.

Call with `rake fix:bvs`.

Trello: https://trello.com/c/D1rIIleb/576-bv-19b,
https://trello.com/c/VCeC7ne5/586-fehlende-bv-zuordnungen

Wiki:
https://github.com/fiedl/wingolfsplattform/wiki/Zuordnungen-zu-Bezirksve
rbänden
User.with_postal_address: adding specs and refactoring to return an ActiveRecord::Relation.
bv assignment: fixing specs.