Saasu invoice due date

[macropin]

The due date is not set to the (saasu setting) default when pushing timesheets to a new sale.

[macropin]

We should be pushing 'tradingTerms' item along with the sales invoice to determine the terms. An easier method is to just set the due date (dueOrExpiryDate) along with the invoice. This could be stored in the service, or the job.