Fix mistakes:
* Accidentally modified BatchBuilderSingle to take contactIds.
  Changed back to using contributionIds.
* It seems we need to call parentPostprocess first in Task forms.
Improved:
* IssueTaxReceiptsCommon now passes exported params to batch issue.
* This means that postprocess is generic enough we can use parent method
  in IssueSingleTaxReceipts.php.
A little more work on Annual Issuing rework.