Confirm transactions only after sucessfully printing coupon

This prevents the data to be commited before sale confirmation, and remain
inconsistent.
- As ocurred with trades, where the product returns to stock, even if the
sale is not being completed.

Print bills and booklets after fiscal coupon printing.
- Fix tests.

Change-Id: Ic9758487d0f6784bd015d9f032c2808fbb6a55e1