[IMP] Point of Sale Useability and code cleaning

addons/point_of_sale/__openerp__.py

addons/point_of_sale/account_statement_view.xml

addons/point_of_sale/point_of_sale_report.xml

addons/point_of_sale/point_of_sale_view.xml

addons/point_of_sale/report/__init__.py

...point_of_sale/report/pos_sales_user_today_current_user.py

...oint_of_sale/report/pos_sales_user_today_current_user.rml

addons/point_of_sale/test/point_of_sale_report.yml

addons/point_of_sale/wizard/__init__.py

addons/point_of_sale/wizard/pos_confirm.py

addons/point_of_sale/wizard/pos_confirm.xml

addons/point_of_sale/wizard/pos_get_sale.py

addons/point_of_sale/wizard/pos_get_sale.xml

addons/point_of_sale/wizard/pos_sale_user_today.xml

addons/point_of_sale/wizard/pos_sales_user_current_user.xml