Sets the CiviCRM default Priceset for the line item, if not already set
We found that the Invoice PDF could not be generated when using the Action Provider, Create Line Item action without also setting a Priceset ID for each Line Item.
This change sets the CiviCRM default Priceset for the line item which is ID 1, if not already set for each line item.
Agileware Ref: CIVICRM-2105