structured error display

[0robustus1]

We should have a more structured error display. Currently we see the error message in a box inside the OntologyVersion list. But we should display more information (for admins):

• The raised Error-Message
• The Full Stacktrace
• OntologyVersion.id, Ontology.id (or better: OntologyVersion#inspect and Ontology#inspect)
• A reason or rrigin for the error: For example, if an admin manually set the ontology to failed, it should be displayed here
  • There might be more possible reasons (please add them here, if possible)

It might be good, to entertain the possibility (and discuss it) if it would be a good idea to add an error-model.

[tillmo]

see branch 572-add_structure_to_error_display