base_location: Don't position zip_id after street2, to avoid layout issues with module partner_address_street3

Currently, when you install the modules base_location and partner_address_street3, you may have the following layout (from top to bottom):
1) street
2) street2
3) zip_id
4) street3
5) zip + city

We could play with priorities of views, but I prefered to fix this issue by attaching zip_id on "div class="address_format". With this PR, you will always get the following order:
1) street
2) street2
3) street3
4) zip_id
5) zip + city