Add new 'internal' attribute on property of document model

By default property with internal attribute is excluded from REST interface
Update default document events

Remove EVENT_CREATE_LOCALIZED, use EVENT_UPDATE
EVENT_UPDATE is now dispatched on correction merged
Add \Rbs\Commerce\Cart\Cart::getPricesValueWithTax() method
Add 'internal' attribute on property 'Rbs_Order_Order::contextData' an 'Rbs_Order_Order::linesData'
Merge pull request #812 from inthause/documents

Add new 'internal' attribute on property of document model