[REF] point_of_sale: migrate to new api

addons/point_of_sale/__openerp__.py

addons/point_of_sale/controllers/main.py

addons/point_of_sale/data/default_barcode_patterns.xml

addons/point_of_sale/data/point_of_sale_data.xml

addons/point_of_sale/data/point_of_sale_demo.xml

addons/point_of_sale/data/point_of_sale_workflow.xml

addons/point_of_sale/models/account_bank_statement.py

addons/point_of_sale/models/account_journal.py

addons/point_of_sale/models/barcode_rule.py

addons/point_of_sale/models/pos_category.py

addons/point_of_sale/models/pos_config.py

addons/point_of_sale/models/pos_order.py

addons/point_of_sale/models/pos_session.py

addons/point_of_sale/models/product.py

addons/point_of_sale/models/res_config.py

addons/point_of_sale/models/res_partner.py

addons/point_of_sale/models/res_users.py

addons/point_of_sale/report/pos_invoice.py

addons/point_of_sale/report/pos_order_report.py

addons/point_of_sale/security/point_of_sale_security.xml