implement initial backend support to validate configurations

[swinkels]

Wiki page https://github.com/lizardsystem/lizard-wbconfiguration/wiki/Validatie explains how the validation of configurations should work. This ticket is concerned with initial support for validation, that is, we need to implement support to

• retrieve the configurations from the shared network folder,
• display the relevant information in the "Configuraties" screen and
• import all the configurations on the press of a button.

Note that in the VSS, the "Configuraties" screen is the screen the user sees when he navigates to the tab "Beheer" and then clicks the "Valideer configuraties" button.

[swinkels]

Well, the functionality is implemented to retrieve configurations from the shared network folder. Still, some work has to be done:

• The actual import of all the configuration still has to be implemented as a Celery task.
• The location of the shared network folder is currently hard-coded as a property of the ZipFileNameRetriever. Of course, a Django admin should be able to set that location in the admin interface.
• The "Configuraties" screen has to be hooked up to the contents of the shared network folder. This is trivial but as the shared network folder is mostly empty, the corresponding view uses a stub configurations retriever that supplies some hard-coded configurations.
• The Save button of the "Configuraties" screen has to be hooked up to the import of all the available configurations.

[swinkels]

In a previous comment I wrote

The location of the shared network folder is currently hard-coded as a property of the ZipFileNameRetriever. Of course, a Django admin should be able to set that location in the admin interface.

In commit 7955d0a05a39a7f0469fc8f0f831368578768222 I have implemented this through a Django setting instead of model attribute. The Django setting is a solution that suffices.