Blackbox tab: consideration for a modification

[Torchi]

The blackbox tab contains configuration information, notably the blackbox logging device, that, if wrongly set, can block the access to the tab itself. The way to come out from this situation is correcting the blackbox logging device via CLI: at the restart after the save, the tab is accessible again.
This field, now input in the blackbox tab, that with its value can make the tab not-accessible afterwards, should be taken out from the blackbox tab and put elsewhere, e.g configuration tab. This is an minor issue, but may be confusing.