MAGETWO-69111: Customer custom address attributes lost after changing contact information and password

- Add attribute set id in customer address

Author: stkorf

app/code/Magento/Customer/Model/Address.php

@@ -378,4 +378,14 @@ private function getAttributeList()
         }
         return $this->attributeList;
     }
+
+    /**
+     * Retrieve attribute set id for customer address.
+     *
+     * @return int
+     */
+    public function getAttributeSetId()
+    {
+        return parent::getAttributeSetId() ?: AddressMetadataInterface::ATTRIBUTE_SET_ID_ADDRESS;
+    }
 }