Made the Calculator return a Value

The test was wrong, and was passing an array instead of a Price\Value. This changes this, and updates the implementation accordingly.
add load function to the VatHandler
added gateway. method implemnentation will follow
Implemented vatHandler
Fixed Calculator test after the change of array to Value
Fixed converter because in the table we have not 0 or 1. We have 1 or 2
Remove fromPersistence function as we do not need it. Also fix a cs issue in the SortInfo
Changed converter and gateway to get the values properly