there is too many log of go-tpc when generate csv

[july2993]

this is bad when the warehouse is large, and user need to redirect stdout to a file

log like this:

load to customer in warehouse 7003 district 10

load to customer in warehouse 7140 district 8

load to new_order in warehouse 7071 district 7

load to customer in warehouse 7075 district 7

[yeya24]

These logs are important to know the current preparation status. If you think there are too many, we can add a silence option in go-tpc. WDYT?