Sets rebate value to 0.00 before adding prices to products and services
The rebate values have to meanings:
1.) Possibility to display the original, not reduced price in catalog list and detail views
2.) Contains the reductions given to customers in the basket
To distinguish between both, the rebate values have to be reset before they are added to the basket
Fixes and improvements, re-adds payment part again
Fixes price calculation and adds line for given rebates
Fixes test when redirecting to confirmation page