erp5_document_scanner: Add preference properties required to configure scannerjs

5 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

00:49:49

passed ERP5.PerformanceTest-Master

00:32:21

failed ERP5.UnitTest-Master

03:34:11

passed SlapOS.Eggs.UnitTest-Master.Python2

00:17:52

passed SlapOS.Eggs.UnitTest-Master.Python3