Reporting - unused rules advanced issues

[tpurschke]

• [ ] make sure the importer gets the latest hit information (e.g. CP is not imported if no config changes are found)
• [ ] add more hit information for the other (non-CP) platforms, e.g. fortimanger 7 last info must be collected separately
• [ ] currently the information that a device has no hit information is "overwritten" when no unused rules are found at all (UI message issue)