Add fees and discount on Cart

Remove CartStorage
Update JSON import / export
Add Rbs_Order_CreditNote document
Some fixes on admin interface (breadcrumb, context, editor, filter)
update admin routes
Rename Rbs_Price_Fee document to Rbs_Commerce_Fee
Add Rbs_Discount module in ECom package
Fix Rbs_Commerce setup. (remove \Rbs\Commerce\Events\CartManager\Listeners)
add CreditNote skeleton admin editor
Enhance Product and Cart
Add variant prices editor
Merge pull request #861 from inthause/documents

New Rbs_Discount module and  cart updates
Merge pull request #863 from loiccouturier/master

Enhance Product and Cart and add variant prices editor
Fix context restoration in shipment and order editors.
Add taxes detail in order editor.
Misc display enhancements in module order's BO.
Fix bad src causing 404 on product variants.
Merge pull request #862 from intportg/dev

Fix context restoration in shipment and order editors.
Enhance display of variant product in FO
Merge pull request #865 from loiccouturier/master

Enhance display of variant product in FO
Merge pull request #864 from fredericbonjour/Admin

Added possibility to save search filters.
Implement fees and discounts on Cart and Order