[Working Capital] New Feature: Exceptional acquisition transactions 

[Working Capital] New Feature: Exceptional acquisition transactions for values over current acquisition limit, requiring management board approval. 
Minor Change: added consistency predicate to make invoice files mandatory.
Minor Change: added exceptional acquisitions approvals to the pending authorization list for management council members.
Minor Change: Created activity for management council members to reject exceptional acquisitions.
Fixed bug, on previous pull request, when selecting processes to show on pending authorization list.