Specified uri as ID in ConceptDto and UnitDto and enabled=false option for certain fields

Closes #333

added Bug scope::Backend labels

requested review from @mweise

assigned to @grantnert48

@mweise I had to remove the enabled = false option from created and columns fields in these DTOs because I would always get an error saying that this option is only allowed on fields of FieldType.Object. Is this okay?

Yes, apparently this is useless anyway and will be overwritten by #322

approved this merge request

mentioned in commit 8bb23619

merged